web cam on serial port.

I need help to connect a connectix color cam. I installed the software and hooked the cam to a data switch box that is hooked to the serial port , next to the parallel port on my xps t600r dimension. When I tried to use the cam it says that the parallel port is being used by another device. It is hooked to the serial port not the parallel port. What is causing this and can I make it work? This is the first time that I have tried to use the serial port, could there be a problem with it, why does it not work?
Thanks in advance for any help you all can give me,
Cheryl