What is preventing remote locking?

Check the video

sounds like remote is faulty you can try to reprogramme by turning ignition on/off 5 times until beep is heard then press any button on remote if lock button does not respond when pressed during this procedure it is FAULTY. you can try pulling apart and cleaning touch pads/switches

If you pushed the car by the door itself or swung the door open hard, you could ha e stretched the door harness and pulled wires apart. There is a little accordian styled boot that 'protects, the wire loom leading to the driver door electronics. I wonder if you have noticed your alarm horn doesnt beep when locking the doors from the remote. Or you can only lock and unlock the driver door only from the driver door. If thats the case there may be an open in the wires leading to the door lock actuator; which controls things like lock/unlock functions of all doors and windows, door warning lights, etc. Have the harness repaired

Try the following:

"KEY FOB PROGRAMMING
NISSAN
SYSTEM DESCRIPTION
The Central Door locking is controlled by the Multi-Remote Control system which controls
the door locking, door super locking and hazard reminder. When the doors are locked and
unlocked the unit flashes the hazard lights once for lock and twice for unlock.
A maximum of four remote controls are allowed to be programmed.
ALMERA
ALMERA TINO
PRIMERA
MAXIMA
MICRA
SERENA
VANETTE CARGO
TERANO II
Ensure all the doors have been unlocked, either by using a good transponder key or remote
control plip key.
Procedure
1. Turn the ignition switch from Position 0 to ON 6 times within 10 seconds.
2. Then turn ignition switch to OFF position. Leave key in ignition switch.
3. After 2 seconds, the system will enter programming mode and will flash the warning
lights twice.
4. Press and HOLD the unlock button on the Plip.
5. While pressing the unlock button, press the lock button 3 times.
6. Release the unlock button.
7. The warning lights will flash once to indicate successful programming.
8. Repeat procedure 4 to 7 for up to 4 plip key?s.
9. When completed turn ignition ON, and the warning lights will flash 2 times.
10. Remove key, and check all plip key?s for operation.
NOTE : The programming mode will stop when either the ignition is switch ON, 4 plip keys
have been programmed or no input signal either from the switch or plip keys has been received
for 120 seconds."

try this one. hold both lock and unlock buttons for about 10 seconds. the truck should beep and the light should flash twice. that switches alarm modes from quiet to loud/on and wiseversa.( hope i spelled that one right).

Trunk Lock After Closing
--------------------------
Desc.: What happens to the trunk lock when closing it.

Settings:
Yes: Automatically lock Boot on closing
No: Boot can be reopened using micro switch button located on the trunk/boot

* Trunk Lock After Drive Off
----------------------------
Desc.: Should the trunk be locked at drive off or after 30 sec.?

Settings:
Yes: Trunk/Boot will automatically lock when vehicle increases speed
No: Trunk/Boot will remain closed, however will be in the unlocked
condition if No was selected in the previous option.

* Door & Trunk Unlock at Key Out
--------------------------------
Desc.: When the is removed from the center console should door/trunk
be unlocked?

Settings:
Yes: All Doors & Trunk/Boot will Unlock when the Key is removed from
the Ignition Switch If Driver frequently locked all Doors when
driving
this feature would be beneficial.
No: Doors and Boot will remain in the same condition as they were
prior
to Key removal

* TSL Locking Logic (Theft Security Locking/Deadlock)
-------------------
Settings:
TSL at first Press: Default Setting. All Doors will lock in Deadlock
Mode
TSL at Second Press: All Doors will lock in Deadlock mode at the second
press of the Remote.

* Lock /Unlock Acknowledge
--------------------------
Settings:
None : No acknowledge will be visible
Indicators: Indicators will blink as acknowledge

* Follow Me Home Function
-------------------------
Settings:
Tail Light: When selected Tail Lights will be illuminated
Back Up Light: When Selected Reverse Light will be activated


Tech 2 Body Exterior Lighting & Horn
====================================

* High Beam Follow me home Active Time
--------------------------------------
Desc.: Follow Me Home Active Time can be adjusted between 0- 10 minutes

Settings:
This Feature can be turned on or Off .Yes / No can be selected.
Low Beam Automatic / Low Beam also in Position 0 (light switch)
Yes / No
Follow Me Home Active Time
- Daytime Driving Lights can be activated

* Parking Lights
----------------

Settings:
Act as Lead Me To the Car Light.

* Park Light On Reminder
------------------------
Settings:
On / Off
If Ignition is turned Off and the parking lights are active, Driver will
be warned if set to on.

* Show Trailer Light Outage
Desc.: REC will detect blown trailer light and display on SID

Settings:
Yes or No

* Trailer Light / Fog Light off
-------------------------------

Settings:
Yes: Fog Light Rear will be disabled When Trailer is connected Yes
No

* Horn Lock Unlock Acknowledge
------------------------------
Settings:
On: Horn will honk when car is locked
Off: Horn will not honk if car is locked


Tech 2 Body Locking
===================

* Panic Alarm Activation (Vehicles fitted with /Alarm only)
-----------------------------------------------------------
- Panic Button / Locking Switch
Central Locking Switch Driver /Passenger

Settings:
- Panic Button on Remote and locking switch inside vehicle will
activate alarm
- Panic Button will activate Alarm only
- Locking Switch inside vehicle (driver /passenger will activate
alarm only
- No Panic Alarm function required.

* Unlock Logic
--------------
Settings:
All at first press : All Doors will open & Fuel Lid will unlock if the
Driver or Passenger Door Switch is activated
Driver Door & Fuel Lid at first press : Only the drivers Door will unlock
& Fuel Lid will unlock when door
switch is activated

* Remote unlocking One Press
----------------------------
Settings:
All at first press: All Doors will open & Fuel Lid will unlock if the
Remote is pressed
Driver door & Fuel Lid at first press: Only the drivers Door will unlock &
Fuel Lid will unlock when the Remote
is pressed

first check the battery in the remote. if it is good it could possibly be the body control module

That sounds like a faulty connection that's been giving you little warnings for a while.

Likely only a loose connection in the circuit that's associated with both the dashboard instrument cluster and your keyless remote.

When you use your remote or insert your key in the Drivers Front door all the door locks should work at the same time by the door lock motors electrically. If you have to manually unlock the door because it will not lock or unlock by the lock motor, you need a door lock motor. The drivers and passengers front doors can unlocked with the key manually only. The rear doors you have to pull up the latch. 
If NONE of doors unlock electrically with the remote or drivers door lock, intermittently or all the time, you will need a Central Locking Electronic Control Module. Pressing the remote button you will hear the "beep", but no door locks will fire at all. 
If you have a few odd door locks not working intermittently or not at all, you will need a new door lock motor for each door lock that malfunctions. You can hear if the door locks are working electrically. Yes, they are common problem. 
If you can hear the door lock motor working but the door still doesn't unlock you need to take the door panel off and lubricate the door latch assembly and work the lock, loosening it up. This is common as well.
Sometimes a bad door lock motor can blow the central locking fuse. You will notice it because it will take a second or two longer to lock and unlock compared to the others. If the door lock motors seem fine, install a the next step up in amperage fuse. (From 15 AMP to a 20 AMP)

hello mate.. if it has stopped working you might want to check the battery first.. if you are sure that the battery is fine then consider reprogramming the fob to your car.. here are the steps to follow.. NISSAN

Remote Control Fob Procedures:

The Central Door locking is controlled by the Multi-Remote Control system which controls
the door locking, door super locking and emergency hazard reminders.

When the doors are locked and unlocked the unit flashes the hazard lights once for lock and twice for unlock.

A maximum of four remote controls are allowed to be programmed:

ALMERA
ALMERA TINO
PRIMERA
MAXIMA
MICRA
SERENA
VANETTE CARGO
TERANO II

Ensure all the doors have been unlocked, either by using a good transponder key or remote
control plip key.

Procedure:
1. Turn the ignition switch from Position 0 to ON 6 times within 10 seconds.
2. Next, turn ignition switch to OFF position. Leave key in ignition switch.
3. Wait 2 seconds then the system will enter programming mode and will flash the warning
lights twice.
4. Press and HOLD the unlock button on the Plip.
5. While pressing the unlock button, press the lock button 3 times.
6. Release the unlock button.
7. The warning lights will flash once to indicate successful programming.
8. Repeat procedure 4 to 7 for up to 4 plip key's.
9. When completed turn ignition ON, and the warning lights will flash 2 times.
10. Remove key, and check all plip key's for operation.
NOTE : The programming mode will stop when either the ignition is switch ON, 4 plip keys
have been programmed or no input signal either from the switch or plip keys has been received
for 120 seconds.

http://www.autokeysquad.com/nissan-fob-programming

i hope this can help you.. :)