[Freesurfer] mri_normalize

I am getting an error running mri_normalize (as part of recon-all) on a particular subject's volume.

Here is the command from recon-all: mri_normalize -g 1 nu.mgz T1.mgz

Here is the output: WM removal version using max gradient = 1.000 reading from nu.mgz... normalizing image... talairach transform 0.860 -0.007 -0.123 -96.500; -0.087 0.643 -0.647 -17.669; 0.096 0.653 0.636 -156.251; 0.000 0.000 0.000 1.000; INFO: Modifying talairach volume c_(r,a,s) based on average_305 MRInormalize: could not find any valid peaks mri_normalize: normalization failed

nu.mgz looks fine, so I wonder what could be the problem. Any ideas?