256 bit encryption

I took a PDF file from DT Pro Office and opened it in Acrobat 9 where I created a security preference that included 256 bit encryption. I saved and closed the file. When I select it now in DT I get “No Selection” in the preview window. Nothing about entering a password either. And the file will not open in DT, but will in Acrobat.
Does DT not recognize 256 bit encrypted PDF files like this?