Auto brake problem

[Zaphod]

Hi all.
Having problems with the auto brakes on Thomas Ruths excellant DC10. I think I saw them working when I first flew the plane but since then I haven't been able to get them to work. Is there a specific proceedure I need to follow? I activate the rotary switch on the overhead panel in the VC but still they don't come on when I land. Auto spoilers work fine as does the reverse thrust.
I don't usually fly the "Heavys" but the VC is soooo good that I love this plane.
Any help appreciated.

Zaphod.