Hi there,

If you have not set the Tx to send a signal to the gyro gain then the gyro will not be active. It sees and indeed it is 0% gain either way, at rate mode and at head holding mode.
So as the gain is 0 the gyro is inactive.

I don`t have such a Tx but I found this.
I think you`ll have to program the Tx through a PC.

Even if you program the Tx you must have the gyro gain knob at heading hold mode before you power the helicopter. As most modern gyros need to be initialized when they are in heading hold mode and not in rate mode.