How was it connected to the TV where it worked?
What kind of TV what is connected to when it worked?
1) Does the tv have a set of jacks in front? If it does try connecting directly there and changing to the appropriate input.
2) If that worked great....now try this. Change everything to as if you are watching a VCR movie. Make sure the movie displays.
3) Without turning anything off, plug the Wii into the VCR inputs and turn on the Wii. If you don't get a picture, then there is a setting in the Wii that is preventing it from working.