Insert>Molds>cavity missing from SW 2008 sp5.0

I cannot find the Insert>Molds>cavity command in my SWOffice Premium 2008 sp5.0. I am trying to do this operation:

Create an assembly with both parts positioned as required. Edit thepart (in the assembly) you want to cavity out. ClickInsert>Molds>cavity and select your inner part as the designcomponent. All done.

Can you suggest any solutions?

Thanks,

Doug Danielson
SolidworksGeneral