Cannot establish blue tooth connection to ipad

Are they near tablet or phone when u setting the upto Bluetooth

It's fairly easy to set up usually. With the keyboard powered on there is usually a button that turns bluetooth on and a (usually) blue light will start flashing. At this point on the iPad you look in the bluetooth settings page and look for the keyboard to appear in the available devices. Tap the link to it and follow the instruction. The blue light should stop flashing and remain lit and the iPad BT settings will show that the keyboard is connected.

On main menu screen swipe down from the top and you will see
Wireless press left arrow and you will see a menu with blue tooth listed .turn on and opair headphones.

Be sure to check your settings to have Bluetooth on

on your iPad go to setting-> then down to bluetooth. on your headed set Press and hold the multi-function button for 10 seconds until the indicator light turns blue. It is now in pairing mode. it should show up on your iPad, click on your headset and it should pair.

check the manual...!
depends on the model - but it works with bluetooth- see a sample :
put the iPad in the slot built into the keyboard, and pair it with your iPad via Bluetooth
On your iPad, tap the Settings icon and then tap Bluetooth. Make sure Bluetooth is On.
Connect the Logitech Ultrathin Keyboard Cover i5 Logitech Support Article

Perhaps you look on this link to see you did everything right, like charging the battery, switching on and pairing. Don't forget to switch on bluetooth on your iPad. SHARKK Apple iPad Air Wireless Bluetooth Keyboard Case

After turning on your keyboard, the blue indicator light will come on for a couple of seconds, then go away. Next, press the button that says "connect" at the very top right corner of the keyboard. It looks like a wifi signal with a circle around it (I had trouble with this part, I didn't realize it was a button). Blue indicator light will start blinking, meaning that it's ready to connect. Go to Settings > Bluetooth (make sure it's on) > click on device. Voila!