Check the yellow indicators on the local and remote modules while no keys are pressed on the keyboard and no mouse movements are being made - both indicators should be continually on when a valid video signal is present.
LOCAL: If the yellow indicator is giving a regular flash (twice per second), then the video feed to the local module is not valid. Try connecting a DVI monitor (preferably using the same DVI link cable as used with the local module) directly to the computer and check for a correct image.
REMOTE: If the yellow indicator is giving a regular flash (twice per second), then the video feed via the link cable is not valid. If the link cable is long, try using a short link cable temporarily to check for basic operation. If the yellow indicators are off, then the link cable is not properly connected