If you can open the database but not replicate it, this probably means that the "Replicate or copy documents" permission is not checked in the database ACL entry that applies to you. In Notes 6.5, you can check this by selecting Database from the File menu and then selecting Access Control. (Actually, it's been a long time since I used 6.5... I'm not 100% sure of my memory of the menus.)
You need to establish which entry in the ACL applies to you.
If you see your name in the scrolling box of entries, that specific entry applies to you.
If not, then look for an entry for a group in the Domino Directory that you are a member of, or for a wildcard entry for your organization (the stuff that follows the / in your full Notes user name). If none of those are there, then you're covered by the -Default- entry. So select the appropriate entry, and look on the right for the 'Replicate or copy documents' box, and I'll bet it's emtpy.
If you have Manager access to the database you can check the box yourself and click OK to update the ACL. If you don't have Manager access, then find your Notes administrator and ask him or her to do it for you.