help with koss ent. system

hello all-
im new here and woulg greatly appreciate any help you can provide. i just purchased a koss 6:1 surround sound system. i can hear cds, hear and see my television/cable through the surround sound but when i attempt to play a dvd, i can only hear the audio but no picture. i am a moran when it comes to setting this stuff up so like i mentioned, ANY help would be appreciated. im also not sure if i have provided enough info so let me know if i need to add any info. thanks for any help!!!!!!

stupic question, you have plugged in the visual cable

You have the sound, so the phono is there, but the visual will go wither S-video, SCART or composite (or coax, hope not).

You might have to use your TV remote to select the correct input method.

I use to have to do that when I has terrestrial via COAX and DVD via SCART. I had to change the TV's visual input method through COAX,COMPOSITE until I got to SCART

just a thought