Headset XLT HS150-K1

I just received this headset From Two Way Radios for use with Kenwood GMRS radios TK3130 (ProTalk) and TK 3131 (FreeTalk). When I connect the headset to either radio, the PTT function works as it should. When I move the PTT/VOX selector to VOX, it automatically keys the radio so that I can not receive incoming transmissions.
Question 1. Is there a VOX sensitivity setting for this headset?
Question 2. Is that the way the VOX is suppose to work or do I have a malfunctioning headset for the VOX mode?