Having trouble to get the headphones to work consistently with my DX. I've only gotten it to work once and I have no idea how I did it...When the headphones are plugged in I can hear the caller but they can't hear me, but once I unplug the headphones the normal mic input on the phone works correctly and the caller can hear me just fine. Are there settings that I need to adjust in order for the iphone headphones to work with DX?