Exception caught in Forward Dynamics

[Alexandra Yurova]

Hi,

i added 6 DoF to patellofemoral joint in Schmitz Model (6 coordinates and 6 spatial transforms).

Exception was caught in Forward Dynamics:

Integrator initialization failed apparently because:
SimTK Exception thrown at SmallMatrixMixed.h:879:
Error detected by Simbody method lapackInverse(Mat<>): Matrix is singular so can't be inverted (Lapack getrf info=3).
(Required condition 'info==0' was not met.)

What can cause this problem?

Regards,
Alexandra