Sheet Metal Parts in Simulation Not Working Anymore

Hi,

I have a model consisting of some sheet metal, some surfaces, andsome regular solid parts. In my static and frequency analysescosmos will mesh those sheet metal parts and surfaces as shells(which is desirable) and of course the other solid parts as a solidmesh.

Trying to do a linear dynamic analysis of the model now, however,cosmos will no longer treat those sheet metal parts with a shellmesh and it wants to mesh them as a solid, which of course I don'twant because I can't get enough elements across the thickness tomake the results accurate without cosmos generating nearly amillion elements which takes too long. If I right click on thesheet metal part in the parts list it gives me a "Treat as sheetmetal" option, but selecting it does nothing. Can anyone tell mewhy I cannot use a shell mesh like normal on those sheet metalparts in the dynamic analysis?


PS I using SW2009 SP0SolidworksSimulation