Cam is not read by the USB port.

I recently installed a Logitech Quickcam Pro 3000. The software was installed properly and the cam was connected to a usb port. but when I started using it, I get a picture showing me to connect the cam to the port even though it is already connected. 1 USB port only works on the live broadcast but when used as a webcam it stops and the IM says cam is not connected. The technicians in the shop were I bought my unit are also wondering about this problem coz they tried the 5 usb ports on a simple mouse and it worked. My motherboard is ASUS CUSI-M SiS 630E AGPset. Tried contacting ASUS but no avail. can you help me?