2 roles: each 1 of them doesn't have to see other's doc

i have this issue:

i want that 2 different Roles use that documents section but each role doesn’t have to see other’s role documents.

so i create a document (as ADMIN, full capabilities), choose the role that can see the doc but, logged into the website with this role’s credential, i can’t see the doc.

i must enable the “edit_private_documents” capability to see – at this point – ALL the documents – which is what i don’t want to happen.

So must be a capabilities issue but i can’t manage to come out from this issue

http://wordpress.org/plugins/wp-document-revisions/