No sound when connecting via docking station

connfailed1

there will be no sound coming from the remote PC when my laptop is in the docking station - so i first have to close the connection/window, take it off the dock, then connect to the PC again and only after the connection has been made can i put it back into the dock again...

it might be something to do with the Hdmi/Monitor audio device, but it is really annoying anyway... (i have already selected the laptop's own audio output/speakers etc...)