Problem with Shell Command

Hi Everyone,

I've imported a STL file from Mimics into SolidWorks Premium 2013 as a "solid body" and I'm trying to modify it. I need to make the inside of my object empty, cause I only need 2mm thickness shell. I've tried Shell Command but it gives me error and I don't know how to fix it. Does anyone know how to do this? I can email you my file, if you want to have a look at it. I can't attach it here cause it's more that 10Mb. if you can do it please let me know.

Kind Regards,

Masoud

SolidworksParts And Features