PDFs with password security will not open on Blackberry tablet

I'm  a designer, pretty clued with everything Mac based. I put password security on PDFs sent out to clients to restrict editing, theft of images, maps, high resolution printing etc.

However, they won't open on Blackberry tablets, if they do, they show as blank, grey pages. The same PDFs without secuity will open. Client tells me he is using up to date Adobe Reader. To be clear, I do not create a password requirement for opening the PDFs, just to restrict editing etc.

Any ideas?

Thanks