ATMEGA 2560 1200 baud wont work correctly

When I run a simple hello message at 1200 baud, it return garbage text, using the same com port running it at 9600 its ok, same board, same program. Any suggestions as to the cause?
Thanks in advance this is very frustrating. It was working.

Did you configure communication to 1200 baud both in your Serial.begin() call as well as in the Serial Monitor menu?

The serial 3 is used and setup Serial3.begin(1200);

The Serial3 port is connected to a laptop running putty at 1200

Its OK guys, it was a flake of solder on the processor pins. Thanks for the thoughts and assistance..

Thanks for taking the time to post an update Vinny56! I'm glad to hear it's working now.