Brakes don't go off

Hi,

my issue with the 737 is that when i activate autobrake the plane does brake until 0 knots and i can't deactivate the brakes. The only way to deaktivate the brakes is to set the parkbrake and deactivate it. I don't have any problem with the 747.

I'm using fsx on 64bit vista, no rudder pedalls.

Any guess?

Thanks in advancce.

Chris Thiele