I have a HDH-300 BT headset which worked fine with a P910i. I have now replaced that with a K750i. But when I go to add a handsfree device, the headset cannot be found. You would have thought a SonyEriccson phone would work with a SonyEriccson headset but I couldn't get a T610 to work either.

Anybody with some ideas what might be wrong?  I am sure the headset itself is okay

Thanks