rem voltage in 05 nissan altima

Hello everyone. I'm new to this game but I think I've done enough reading and watching youtube vids to have a basic understanding of what I'm doing. Instead of me writing a diatribe about how I'm hooking everything up, I think this vid will explain it better. My setup and testing Thanks for your help.

The blue remote turn on lead on the amplifier needs to be connected to a 12V switched source to turn the amplifier on. Typically this would be connected to the remote turn on lead from your head unit, however if you have a factory head unit, you'll probably need to connect it to an accessory lead in the vehicle such as the switched lead going to the factory head unit. When power is removed from the remote turn on lead on the amplifier, the amplifier will turn off. the12volt • Support the12volt.com

That's what I did. I tapped into the existing remote wire for the factory amp. With the car off and just the acc on, it registers about 10 volts. When I start the car and the alternator takes over, it's up in the 12.5 range but it still isn't turning on the amp. Could a bad ground do this? I just took a wire wheel and skinned it down to bare metal in the trunk close to the back seats.