[Freesurfer] load_nifti.m - empty header

Dear Freesurfers,

I am struggling with a very basic step at the very beginning of my processing pipeline. This is what I've done: registered BOLD to anatomical data using bbregister, results checked with tkregister2 - all seems fine. Then I want to project BOLD data to the surfaces using mri_vol2surf - no error so far. BUT when trying to load the mri_vol2surf output into matlab (load_nifti.m) I get this error:

*??? Attempted to access hdr.dim(2); index out of bounds because numel(hdr.dim)=0.* *Error in ==> load_nifti_hdr at 121* *if(hdr.dim(2) < 0)* *Error in ==> load_nifti at 80* *hdr = load_nifti_hdr(niftifile);*

It seems that the hdr struct is completely empty.

Thanks in advance for any kind of help, have a nice week,

Nadine