Regarding Creating contacts

Hi,

I am Raunak, I am working currently with UCSC. I am working with the walking tutorial. I have created a part "footwear" and I want the model to be able to detect contact between the foot and the footwear. Can anyone please guide me ?
I tried doing it in exactly the same way as given in the tutorial on walking ie by replacing the surface marker .World.ground.flr by a marker on the footware. But I am getting the following errors when I run the forward dynamics simulation.

"ERROR: The X values for spline .World.Britney_TRACK_SPLX are not increasing at N=27, X=0.220000
ERROR: The X values for spline .World.Britney_TRACK_SPLY are not increasing at N=27, X=0.220000
ERROR: The X values for spline .World.Britney_TRACK_SPLZ are not increasing at N=27, X=0.220000
ERROR: The X values for spline .World.Britney_TRACK_SPLa are not increasing at N=27, X=0.220000
ERROR: The X values for spline .World.Britney_TRACK_SPLb are not increasing at N=27, X=0.220000
ERROR: The X values for spline .World.Britney_TRACK_SPLc are not increasing at N=27, X=0.220000"

Please suggest what to do.
Thanks