Using MS Gate on a Sony Clie

When I load MSGate on my Clie SJ33, I can see a list of a)databases on the
Clie and b)files on the MemoryStick.

When in mode b), looking at files on the MS, there is a button "MOVE". I
expected to be able to take photos using my Sony digicam, and view them on
the Clie. This works fine, but I'd like to move selected files to
alternative locations on the MS. Selecting the file and using MOVE seems
the sensible thing to do... but whenever I try this, I get the error
"Current folder is access inhibit" (sic).

The MS is NOT read-only, and I have already formatted it with the Clie (as
opposed to formatting it on the camera, if there is a difference). Am I
doing something wrong, or if not, what is the MOVE button for?