Car stereo not working?

Ok I have a 64 chevy truck and it didn't have any wiring ran for a stereo. So I mounted a stereo and speakers. Hooked the yellow wire to the battery, red to the ignition and black wire grounded to the cab in a good place that's bear metal. Hooked it to the battery cause the teminal in the fuse box was broke. I'm not getting anything out of the radio. So I tried switching the red and yellow wire thinking I had it wrong and still nothing. Stereo was working when I pulled it out of my other truck a few months ago. Who knows what could be wrong??