Spectre/RF Matlab Toolbox

I am running mmsim  12.11.203 and Matlab R2013a (8.1.0.604) 64-bit.

When I use the function cds_srr Matlab crashes with the following message:

"This error was detected while a MEX-file was running. If the MEX-file
is not an official MathWorks function, please examine its source code
for errors. Please consult the External Interfaces Guide for information
on debugging MEX-files."

and in the matlab shell:

File voHier.c, Line 98, Function noname *FATAL* Unable to find the location of the cds_root executable.

Any idea about this issue?

Thanks in advance,

Pietro