[Freesurfer] MRISunfold error

Hi, I run "mris_flatten" and got this message: "reading patch ../subjects/shiva/surf/lh.occip.patch.3d with 6095 vertices (98.2% of total)removing ripped vertices and faces...removing ripped vertices and faces...reading original vertex positions...minimizing metric distortion induced by projection...MRISunfold: could not open log file lh.occip.patch.flat.out" It's probably a very simple matter of fixing the unix permission, but I have no idea where MRISunfold is trying to save to. I checked every directory under the subject and found nothing unusual. Does anyone know which directory *.flat.out goes to? Thanx. Hsin-Hao