vipor 791 remote problem

I have a Viper 791, it was installed a month ago may be two.  It worked fine and then all of the sudden the remote doesn't work any more.  I get the symbol that says the remote and the unit is not communicating.  I was hoping that it was out of sync and just pressing lock several times would fix it, but it did not.  Does any body know what happened and how I can fix it?

The problem was just like Gus said.  1 of 3 solder joints on the little sister board.  On this remote it was the 3 pin that was loose.   He told me too:

Take a very close look at the female portion of the connectors, especially where they are soldered to the main PCB. Wiggle them a bit to see if there are broken solder joints..... chances are, there is. The pads where the connectors are soldered are very tiny, and they don't stabilize the connection with any adhesive.

Thanks for the help!