When the CG is not keying properly, graphics will look washed out, flattened with no transparency, or won't display at all.
Take a look at the output of the Compix up on Preview. If both the video and key output look fine on Preview, the DSK or keyer is not configured properly.
Make sure the cabling is in working order. BNC cables can easily get damaged if not properly coiled.
If you do not see anything on Preview, or it looks distorted, try connecting the Compix system straight into a video monitor to see if the issue is the Compix video output. Disconnect any video input or sync to the Compix so it does not interfere with the output to the monitor.
If you do see video when connected straight into your monitor, then the switcher input used might not be setup for the correct resolution. Many switchers are multi-formatted; you'll need to set up the switcher to properly accept the resolution you would like to work with.