RS232 300 baud communication problem

Question

Hi,
I'm writing a program for communication with RS232. The device works to 9600,8,N,1 and 300,7,E,1.
If the program is used to 9600 it works properly, while when I use the 300 baud it doesn't work.
Are there any problems with communication at 300 baud in C#?
For the reading on the RS232 I use serialport.ReadChar(). Can I use it at 300 baud?

I'm usign  System.IO.Ports.SerialPort as library.

Thanks,
Gerardo