steroe trouble

i wired in a new headunit to replace my factory headunit i got it all wired in radio comes on and works ok but no sound is coming out of the speakers its an 8 speaker set up with a built in tape player with the factory added optional lower cd player is there something i'm missing?

i wired in a new headunit to replace my factory headunit i got it all wired in radio comes on and works ok but no sound is coming out of the speakers its an 8 speaker set up with a built in tape player with the factory added optional lower cd player is there something i'm missing?

Grounded correctly?

What type of headunit are you trying to install, is it an aftermarket one? Also, how do the 8 speakers attach to the back of the unit, are there 16 wires for them, or 8 wires with an amplifier or crossover located in the door somewhere?