MSComm and Win NT

I am using a MSComm control in my project. My development machine is Windows 2000. When installing my project on a Win95, Win98 or Win 2000 machine it works fine. However, when installed on a Win NT 4.0 machine my software fails to communicate. This is not just one occurrence, I have tested on 3 different NT machines. The NT machines have Service pack 5 installed. Any suggestions?

Check your version of MDAC. We are running SP6 on NT and MSComm works fine.

Thanks barrk for the reply. It turned out to be a data ground problem.