Serial port 2 is the one labeled "TTL" (not the tether) and depending on which camera port you connect to it usually requires the tiny TTL-converter chip that came packaged with, but separate from, the camera board.
You'll want to keep your PC connected to the Program port while you test the camera, so you can see the status messages displayed to tell you what's wrong (or right) with the camera.
Did you look at the T-packet description?
http://kevin.org/frc/CMUcam2_data_packets.pdf
Yea, CMUCam issues should be posted in the CMUCam sub-forum, but we'll forgive you.