XPS L501X and BT Dongle

Hallo

I have  an XPS that has not the built in BT card.

Since I have a nice BT Headset (BH200) from my old XPS i bought a BT dongle.

Windows recognized it and installed the drivers, all seemed to be ok. I paired the headset. ok.
On the fly i started a movie and sound was perfect.

PROBLEM: as soon as the microphone gets active (for example starting Skype or entering in the recordin settings in the windows mixer)  it stops working. I paired another BT headset and seems the problem replicates.

I updated the Renesas USB3.0 Host Controller. Nothing.
I wanted to download the Broadcom DELL driver but it installes only if you have a built in card....

What can i do??