I'm not a wizzard on these things, but I will do what I can to see if you can get it up, so to speak...
Do you have know where the link status and power lights are in the camera? What are they both doing? They can be flashing, solid on or off. Hopefully they are both lit, but you need to tell me what's up with them. I've included a jpeg with them labeled.
If you don't have a positive link, then check that you are line of site, usually a large loss of signal if not line of site (LOS). Are you using the monitor as a stand alone unit?
Let us know...
Jack