rest_spm_slice_vol.mexw64: access is denied

 Dear rs-fmri experts,

I am trying to use REST to do functional connectivity analysis, but when I just pressed the "run" button, it reported an error: 
??? Invalid MEX-file
'F:\REST_V1.8_130615\rest_spm5_files\rest_spm_slice_vol.mexw64': Access is denied.

Does anyone know what cause it? Any ideas? 

Thanks very much in advance!

Best,
-jt