Head Unit

[Mo Fo 9 <MoFo9@aol.com>]

While attempting to install my new head unit ( Panasonic DP695 to work
w/factory CD Changer), I encountered a problem.  I did what everyone has
told me and only connected the positive wires for the speakers, everything
powers up great, but no sound, I didn't blow the speakers cause I
reconnected the factory head unit and all is well.  I think it has something
to do with the ground wire (black Wire).  Should this be grounded??

Any help greatly appreciated!!

- -Jason