We are ready to help you. I kindly ask you to be more specific. Please, let us know what value you assigned to Flow control.
There are three commonly used modes:
None: CHSh:0x1, FR:0x40
HARDWARE: CHSh:0x1A, FR:0x80
Xon/Xoff: CHSh:0x1, FR:0x43
We would recommend you to use InitString for initialization.
Please, note that if everything works fine only when you open and close the port in another application fist, then the COM port is not set up correctly.