Dear FS Experts

I am having continued issues with the mri_normalize function on MPRAGE data

I get an error message: 

3d normalization pass 1 of 2

error: No such file or directory

error: MRInormFindControlPoints: could not find enough control points

error: No such file or directory

error: MRInormFindControlPoints failed

Can you advise on any reason this may be happening?