Hello all,

When attempting to estimate a design with the rWLS toolbox, I keep getting the following error:  

SPM8: spm_rwls_spm (v$Rev: 3.0 $)                  21:51:28 - 13/02/2012
Initialising parameters                 :                        ...done
Output images                           :                 ...initialised
Plane   2/64 , block   1/1              :                ...saving planeFailed  'rWLS Model estimation'
Undefined function or method 'nansum' for input arguments of type 'double'.
In file "/Users/fritz_0199/Desktop/spm8/toolbox/rwls/spm_rwls_spm.m" (v3468), function "spm_rwls_spm" at line 818.
In file "/Users/fritz_0199/Desktop/spm8/toolbox/rwls/spm_rwls_spm.m" (v3468), function "spm_rwls_spm" at line 945.
In file "/Users/fritz_0199/Desktop/spm8/toolbox/rwls/spm_rwls_run_fmri_est.m" (v3327), function "spm_rwls_run_fmri_est" at line 44.

The following modules did not run:
Failed: rWLS Model estimation

The design specification works fine, but this error always occurs during estimation.  Any ideas what might be happening?

Any help is greatly appreciated!