Need Help setting up two computer match using a Null modem

[bigo]

I'm having problems setting up a Two computer match using a null modem cable, i have a usb to serial cable connect to the null modem cable, the usb part is connected to my laptop, the other end is connected to my desk top computer. I'm using windows xp, I had to download drivers for the usb to serial cable, when I connected everying and set up the match in both chessbase interfaces nothing happened. I set up the laptop on port 1 and the other cable to the same. No results nothing happens what am i doing wrong. ? I couldn't find any documentation on the correct steps. I'm using chessbase interface on both computers. Same operating system on both

[Murat]

I would first test the usb to serial adapter by hooking up a regular serial device, like a printer first.