Model Compile Error - unknown bone reference

[Redeye_Jedi]

I'm trying to compile a custom character model out of Maya 2008 using the Prall 2.4 SMD exporter and the SMDs seem to export correctly but then I get this error when I try to compile:

ERROR: unknown bone reference ‘ValveBiped.Bip01_Head1’ in weightlist ‘fullspinenohead’


I tried to look this error message up in the errors listing but didn't find it in there.

Has anybody run into this error before or have any idea how to solve it?

Thanks a lot for your time and help!

-Ben