I have a 69 Glasspar Cutlas and I am trying to build in a DUAL Marine
AM/FM/CD receiver, but when I hook everything up the unit will not
power on. I have tried a variety of things. I tried hooking up ground
to some metal parts on the boat, and I even tried hooking it up to
Negative on the battery. I went out and bought another stereo system
to see if the first unit was bad, but this new unit won't power on
either.

The battery on the boat is in great shape, and the wiring is done
correctly. I have a fish finder that works off of the same battery and
it powers on fine.

The radio is going straight to the battery, and all the fuses are good.
For testing purposes I'm hooking both power (red) and switched power
(yellow) to the battery. The voltage on the battery is also correct.

Does anyone know what I'm doing wrong here? It must be something small
I'm forgetting here... but I just can't figure it out.

Any help would be appreciated!!

Thanks