Hi all, 

I have a binary mask that I'd like to register to an MNI-normalized anatomical ("wbrain.nii"). 

I'm trying to use the output file from the SPM MNI normalization of the anatomical ("y_brain.nii") as the deformation field to register a binary mask which is in native space to the MNI-normalized brain. 

This has worked for me on two different registrations of a native-space mask to the "wbrain.nii" file, but is currently producing the error: 

> In spm_maff8>loadbuf (line 78)
  In spm_maff8 (line 25)
  In spm_preproc_run>run_job (line 105)
  In spm_preproc_run (line 41)
  In spm_run_norm>normalise (line 72)
  In spm_run_norm (line 23)
  In cfg_run_cm (line 29)
  In cfg_util>local_runcj (line 1673)
  In cfg_util (line 953)
  In spm_jobman>fill_run_job (line 456)
  In spm_jobman (line 231) 
Warning: Matrix is singular to working precision. 

Has this happened to anyone else, and is there a way to fix it? 

Any help is much appreciated! 

Best,
Anna