why won't the VCR side of my DVD/VCR work?

[rsavedin70]

I hooked it up to the T.V earlier and the dvd plays, but when you switch it to VCR, it won't switch. it reads that its still on the DVD side but if i push play on the VCR side, i hear sound but no picture. i don't understand what's going on? anybody know? thanks for your help....
i put in a movie and the picture won't show, just a blue screen, but with sound

 

[RMR]

you may need 2 sets of AV (audio video cords the yellow white and red ones) plugged in the back it really depend on the brand you have