[Freesurfer] niiRead error

Hi, I'm trying to register to the surface a *t*-test map created with afni (3dttest++) but I got this error message:

mri_vol2surf --mov movierestTest.nii.gz --regheader fsaverage --surf-fwhm 3 --hemi lh --o movierestTest_lh.nii.gz

srcvol = movierestTest.nii.gz srcreg unspecified srcregold = 0 srcwarp unspecified surf = white hemi = lh reshape = 0 interp = nearest float2int = round GetProjMax = 0 INFO: float2int code = 0 niiRead(): 5 dimensions in /media/francesca/DATA/Shared/fmri-experiments/fc_categories/searchlight/tesrest/movierestTest.nii.gz; unsupported Invalid argument ERROR: could not read movierestTest.nii.gz as type 24

Thanks Francesca