compustar or nustart problem

I just got the nuStart NU8000(AS) 2-way alarm and starter combo installed yesterday.  The system and remotes are absolutely the same as the Compustar 2W900FMR.  The problem is, after I've got it installed through an Compustar authorized dealer, it was working perfectly fine, but only for 3 hours.  The 2-way remote is sending signal to the car and the car received the signal (no matter is arming / disarming / starting or shuting off the vehicle), but it doesn't respond back to my 2-way remote (hence, it was working fine before and the 1 way remote has no problem at all), and the little signal strength indicator on the 2-way remote is showing "no signal". 

I've tried to replace the battery, reset the remote, turning the vibrating and RPS function on / off, but still not receiving any signal at all.  I'd also tried to unplug the antenna and plug it back, did the 5 times ignition on / off remote learning thing as well, but still no luck.  Can someone help me to figure out what was the problem?  Is my 2-way FM remote (Nu8000R), the antenna (Nu4000 ANT), or the brain (CM3000) having problem?  Many thanks in advance.

I brought my car back in to the place that I got the system installed.  The installer tried to put another brand new antenna and remote from the newer version of Compustar system (Compustar Pro P2W9000FMR) , and it wasn't quite working properly.  It can only be armed with the 2-way remote from the newer version but nothing else.  Shortly after that, he put back the original antenna and re-program the original remote from nuStart, and it works all of a sudden.  Now, the original antenna and remote are working perfectly fine.  Even the Installer couldn't tell me how could that happened.  Wierd......  Can you explain why, so that if it happens again, I would know what exactly should I do, please?  Thanks!!!