Remote Buddy relies on IOKit for recognizing existing and new 
instances of a IOUSBDevice object that represents a certain USB 
device. If Mac OS X knows about the device, Remote Buddy will 
automatically know about it, too.

Please have a look in System Profiler's USB info the next time your 
device is connected but does not seem to be recognized. You shouldn't 
find it listed there either. Which then means this is an issue at the 
OS or hardware level. In that case, this Apple document may provide 
you some help:

http://docs.info.apple.com/article.html?artnum=58033

Detaching the receiver and resetting the NVRAM and PRAM may also help:

http://docs.info.apple.com/article.html?artnum=2238

Doing the latter helped me years ago when Apple's USB keyboard and 
mouse would not be recognized by a certain USB port (I'd always have 
to replug them - or plug them into another USB port).

Best regards, 
Felix