How do i connect a Grundig GDV 720-ht surround sound sytem to a Hitatchi L32HP04U television?

-I have connecte the system to the tv with a SCART lead and can watch DVD's with amazing surround sound. but don't seem to be able to watch the television through the surround sound system. Have tried AV cable with no joy, also tried RCA to RCA cable, also with no joy