This feature works fine on GTalk originated calls according to our test.
However, we are thinking that you might have your GTalk caller in your circle of trust, then, this feature won't apply. That is to say, if you are calling from GTalk, and you will hear AA, then, if you press "1" to go on ringing the phone, "CallForwardOnNoAnswer' won't apply because the call is answered.
Please reply to us on how you made the call (whether or not through AA) and whether or not your GTalk caller is in your circle of trust.