Saitek X52 Pro rudder pedals prob

Have recently started re-building FS9 from scratch as I have now installed Windows7.

I went through the task of re-assigning the various functions to my Saitek X52 Pro joystick and rudder pedals. I cannot however assign the left and right brakes to the rudder pedals. When I click on "change assignment"and press the corresponding pedal absoloutely nothing happens.

When I test the pedals in calibration they are working fine. When I try using the pedals in flight they pitch down the elevators and affect the ailerons, so FS9 is definitely picking them up.

Any ideas?