problems with alphasim

Hi, I am trying to run alphasim and keep getting the following error message: I've tried various masks. The error below was after I applyed the brain mask dparsfa created. Any help is much appreciated. REST Version: 1.5, Release: 20101101 ??? Undefined function or method 'normrnd' for input arguments of type 'double'. Error in ==> rest_AlphaSim at 61 fim=normrnd(0,1,nx,ny,nz); Error in ==> rest_AlphaSim_gui>pushbuttonrun_Callback at 55 rest_AlphaSim(mask,outdir,outname,rmm,fwhm,pthr,iter); Error in ==> gui_mainfcn at 96 feval(varargin{:}); Error in ==> rest_AlphaSim_gui at 27 gui_mainfcn(gui_State, varargin{:}); ??? Error while evaluating uicontrol Callback ??? Undefined function or method 'normrnd' for input arguments of type 'double'. Error in ==> rest_AlphaSim at 61 fim=normrnd(0,1,nx,ny,nz); Error in ==> rest_AlphaSim_gui>pushbuttonrun_Callback at 55 rest_AlphaSim(mask,outdir,outname,rmm,fwhm,pthr,iter); Error in ==> gui_mainfcn at 96 feval(varargin{:}); Error in ==> rest_AlphaSim_gui at 27 gui_mainfcn(gui_State, varargin{:}); ??? Error while evaluating uicontrol Callback