Mute Call On Phone Flip Not Working...

[Sim-X]

So I checked in HKEY_LOCAL_MACHINE\Software\HTC\PHONE and FaceDownMuteRing is set to 1 (I never changed it) but I wanted to double check it was on. So I went into the G-Sensor and did a calibrate. It calibrated fine and the virtual levels are working perfect. When someone calls I go to turn the phone upside down and it doesn't work at all. I tried a number of different ways. Just keeps ringing. I would find this to be a very useful feature at least for me. Any ideas on why it wouldn't be working or has anyone else had a problem?