This has been hinted at but let me see if I can clarify what's going on for me.
I have one category where Act as Members' Category is set to Yes. In this category I have logged in as a registered member and added photos. OK so far.
Issue 1) When viewing an image in the members category (showimage) the member's name appears in the navbar as Member's Album > Joe's Images
but the link points to http://www.japan-101.com/photos/browseimages.php?
hence you get "No Category specified. If you followed a valid link ..." when it is clicked.
Issue 2) When viewing the member's category (browseimages) the member's name does not appear in the navbar, just 's - as in apostrophe + s.