Question [Q] No voice from bouetooth when skype

When I call others with skype, I connect bluetooth earpiece to the phone, but no voice comes out from the bluetooth, and no voice from the phone neither.

Steps:
1. Call others with skype
2. In skype communication, connect bluetooth earpiece to the phone

Results:
no voice from the bluetooth, no voice from the phone speaker neither.

How to resume:
call again with bluetooth connected.

OS: android4.2