Macbook Pro detecting display, but nothing shows up.

I tried to search but couldn't find anything. We have had multiple 1st Generation MacBook Pros updated to 10.5.X that will detect another display but nothing will show up when connected to our Crestron C2N-MMS multimedia switcher. Mirroring on, resolution is 1024x768 and no signal is detected by the projector. It detects the display as "T703 Display". My 2nd Generation MBP detects the setup fine.

The workaround I have been using for now is to put a VGA splitter between the Crestron and MBP.

I am wondering if anybody else has had similar problems and if/how they were resolved.

 

I searched macfixit but couldn't find anything specific to external displays.