Are you using a NULL modem adapter? Serial ports come in two flavors, DTE and DCE. Data Terminal Equipment is the side that provides the user display (the PC). Data Communication Equipment is the side that transmits the information (typcially a modem). One transmits on pin 2 and receives on pin 3. The other is the opposite. In order to connect two DTE devices together, you have to use a null modem adapter, or swap the wires manually.
If you purchase an RS232 tester that has the LEDs on it, you will be able to confirm that each side drives the proper pins.
- Michael