Keep fooling with it. It doesn't work the same way as other vehicles.
I have a 95 Suburban with identical controls (and instrument panel) and am constantly irritated because they don't work the same. It might have somethng to do with the 'drive by wire' trhottle control.
You could also check the brake switch to make sure that it is adjusted properly.
2001 Winnebago Adventurer, 35U, W-20 8.1
F+R Trac bars, F+R sway bars, SafTsteer, F Sumo Springs, 4 Koni FSDs