My car radio will not display station are...

The original radio in my 1997 Toyota Camry and a second hand alpine radio I purchased both no not display any info where you would view the stations. all other lights are on and I can here music. I can change stations, but I can't see what radion station I'm on. I cleaned both battery terminals and checked the voltage from the Yellow wire (constant voltage) and Red wire (Voltage when car is on). The wires from the original harness to the radios were connected Red to Red, Yellow to Yellow, Black to Black, plus the speaker wires. I'm at a loss for additional ideas. Please help. Thanks