First, I would do this in the form builder. Place the control on the form. Second, did you open the port and check to make sure it is open?

Ken Blum put a great comm port testing tool on here awhile ago. It is perfect to test your ports and includes the proper setup code.

You can download it on my site if you cannot find it at:
http://www.crewchiefpro.com/commport.zip