When are the two signals different?

Although you have solved your problem, I will answer this question for posterity.

The difference between the blue Antenna wire and the blue Amp Remote wire is as follows:

- The Blue Amp Remote wire is meant to turn on the amplifiers in the car. It is active whenever the player is supposed to be making sound (which happens to be whenever its display is turned on). This counts even when it is playing MP3 files and you are not listening to the radio. It is only inactive whenever the player is completely turned off, or when the player is in standby mode.

- The Blue Antenna wire is meant to raise and lower a powered antenna, and/or to power an antenna signal booster. It is active whenever the tuner is supposed to be pulling in a signal. For instance, whenever you are tuned to a radio station or when the RDS Traffic Announce (TA) feature is on. It is inactive whenever the player is turned off, or when you are listening to the MP3 or AUX sources with TA turned off.

Hmm. This sounds like it should be a FAQ entry.