serial port problems

I'm creating this code that will operate a scale. I'm using a 9pin serial cable and operating at 7-O-1 at a baudrate of 1200. I want to receive and send information using inp and outp. I was using ProComm, a terminal progrom for DOS, to send commands to the scale by using the keyboard but used a shell to go back to DOS. We using Borland C++ in DOS through this shell my program works fine, it receives and sends perfectly, but when I'm not in this ProComm DOS shell, it will send all right but nothing will be recieved. Any Ideas on why? I think something has to be with the fact that the COM port is not open but I don't know why. Any help will be great.