Problems with OSD/ APM 2.8 configuration

I currently have an Ardupilot APM 2.8 flight controller c/w 100mW telemetry fitted all fully operational. I am experiencing problems however in getting the OSD unit to operate in conjunction with the board.
I have loaded Araucam-OSD firmware and CharSet,undertaken Cofig (Pal camera) and setting up panels 1&2 and saved to OSD.
I have connected the OSD directly to the telem port with the camera and transmitter powered and connected as per the diagrams in the numerous blogs on this subject. My problem is that the screen is blank. Disconnect the camera video feed I get the OSD display. Reconnect the camera video feed and disconnect the OSD feed and I get picture.
Any thoughts or assistance would be appreciated. ( And yes I have toggled the Pal/ NTSC settings in the config panel with no apparent difference)

Hmm so just to be clear, when you dont have your camera connected to teh OSD, you are able to see the OSD on your video feed with a black background? If that is the case have you tried to bypass the OSD to make sure your camera is working correctly? Also make sure your camera and OSD are getting enough power to run them both at the same time as some OSD modules require a significant amount of current to operate properly.

Thanks for your reply. Your last point was the key -insufficient power to run OSD, camera & transmitter. Power set up modified and all is now working fine.