[Freesurfer] mris_calc problem

I have ran into a problem with mris_calc using Freesurfer 5.1 on Mac OS Leopard. When running long_mris_slopes I am getting this error;

ERROR 1 : mris_calc compute sym. pct. change (spc) problem?

It seems to running properly until it hits; mris_calc -o /Volumes/larry/cluster_results/1007base3/surf/lh.long.thickness-spc.fwhm0.mgh ./tmp-1007base3_lh_thickness_PENQ8v/beta1.mgh div ./tmp-1007base3_lh_thickness_PENQ8v/beta0.mgh

The ./tmp files do exist whern mris_calc is called. I have seen on the Wiki that a fixed version of mris_calc is available for Centos. If you think I could be running into the same problem, is a fix available for Leopard?

Thanks, Kevin Department of Neurology University of Wisconsin-Madison