Cannot run program "vsim"

Hi,

When I try to verify a demo design in DSP Builder, I am getting the following error:
"Cannot run program "vsim":....The system cannot find the file specified".

But I have set the path of vsim.exe in the "File\Set Path" of MATLAB window. I can open the Modelsim by typing the command vsim.exe from the directory where it is present through the command window.

If I type vsim in the MATLAB window, it says "undefined variable or function".

Can anyone please help regarding this?

Thanks.