Webcam conundrum

A very basic question here. I run Windows XP Home SP2 on a Fujitsu LifeBook. I just bought the Creative Live!Cam Vista IM webcam. It captures (fine quality) whatever the camera is pointed at but I cannot persuade it to transmit outbound when talking on Skype.

I get the incoming live stream from correspondents on their Logitech webcams. Is there some hidden button on the Webcam Centre that I cannot find to activate to actually transmit?

Any help would be welcomed.