No DVD picture while playing Panasonic SC-HT920. My problem is while playing DVD's on my Panasonic

Question

My problem is while playing DVD's on my Panasonic SC-HT920 I only get sound and not a picture. I think my main problem may be the age on my 1989 46 inch TV. Although I think if I can get sound there is something that I can do to get a picture. The TV has 3 Video ports(red, white, yellow) on the back of the TV. The TV also has 2 Audio ports(red, white) on the back. I have the Video out from the Home theater going to The TV's yellow Video port and the adudio posrts connectewd from the Home tHeater to the TV.. However I cannot get the picture to come in. Another problem I may have is that my TV does not have any option to bring up the Blue screen to change the video settings. There is cable on the TV and we have Road Runner hooked up. Do you have any suggestions? my email address is [e-mail]