material assigning

I m new user of hfss 9.0 and I have little but unsolved problem.when i creating my design I did not assign materials to some of the objects and in the end i cannot.When i select the object, assigning material option becomes inactive.How can i solve this?

Hi,
In HFSS 9.0, the material of the unassigned object is vacuum. you may double click the object that you want to assign material, and a dialog box will be appear, you click "vacuum" , and then you can assign material. oK!

Hi,
You go to history tree. In the model tree, there will be a subtree for unassigned materials. Go to the unassigned material box: Right-click-->Edit-->Properties. Click on material then a list of material will appear you choose the one you want to assign or you can create a new one if you know the epsilon and other material properties. Then click Ok. That way you can change the material properties later on also. Hope it helps.
Regards,
Rex