SoftProof is disabled when trying to preview from Print menu - why?

Hello,

When I do a preview from a Print menu, I notice that SoftProof button is disabled. I am not sure why. Here is what Apple Finder Help says:

"To see your printer’s color capabilities in the preview, select SoftProof at the bottom of the window. For example, if you’re printing a color document to a black-and-white printer, clicking SoftProof previews the document in black and white."

Nothing else. Would it be disabled if my document is color, and my printer is color? Would it be disabled if I connect to it via JetDirect and not AppleTalk?

Thanks,

-Dima