After Market Stereo, "Audio Off"

I've replaced the factory stereo on my '05 Prius with an Alpine stereo, I also used an adapter to allow me to keep steering wheel controls. When I first power on the car, the radio comes on for a moment, then gives an "Audio Off" message and the sound becomes muted. If I turn the car off and quickly back on again, though, the radio works just fine along with all steering wheel controls for the whole drive. Sometimes, instead of going fully muted, the sound simply goes in and out as if someone kept hitting the mute button.

The fact that the stereo works perfectly on the second on/off of the car leads me to believe everything is connected just fine, but I can think of anything else to check.

(BTW, simply turning the stereo on and off again doesn't help, and I didn't use the 68 ohm resister mod mention in other threads since I still have climate control and everything else anyway.)