Can't move article! (in nnml folders)

[Steinar Bang <sb@metis.no>]

Platform: rgnus 0.80, tm 7.100.3, emacs 19.34

Occasionally I get the message "Can't move article!", when I attempt
to move an article from one nnml group to another, using
	B m
in the summary buffer.  Other articles can be moved without problem
(on a set of process marked articles, some are moved, others are left
untouched).

What I do then, is to do a
	B c
and then delete (or whatever terminology larsi has for it) the
article, and let it expire.

But I'm kind of curious, as to what causes this, and how/if it can be
fixed.  Or am I the only one seeing this behaviour (I've been seeing
it for as long as I've had nnml folders, which may be all the way back
to the vanilla Gnus of 19.34 (version number escapes me, at the
moment)).


- Steinar