Hello Freesurfer friends!

I'm going through the "paired analysis" tutorial and am running into an issue with the mri_glmfit. I am running on just one subject pair. https://surfer.nmr.mgh.harvard.edu/fswiki/PairedAnalysis#Runmriglmfit

I ran mris_preproc on my 2 timepoints and am getting an error at mri_glmfit

  mris_preproc --target fsaverage --hemi lh \
   --meas thickness --out lh.paired-diff.thickness.mgh \
   --fsgd pairs.fsgd --paired-diff

mri_glmfit \
 --glmdir lh.paired-diff \
 --y lh.paired-diff.thickness.sm05.mgh \
 --fsgd paired-diff.fsgd \

--osgm \

--surf fsaverage lh

I am getting an ERROR: DOF = 0.

MRI's have been put through recon-all and are in there own directories within SUBJECTS_DIR. 

What is the cause of the error?

Thanks,

Ken

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