When I post a follow up to a newsgroup, the send operation fails.

This bug occurs every time I send a follow up.  I am able to post an article to a 
newsgroup without a problem.  This only occurs on a follow up.

If I start pan from a terminal, and try to post a follow up I get the following 
messages:
(pan:1889): pan-CRITICAL **: file task-post.c: line 138 (build_nntp_message): 
assertion `g_mime_message_get_header (message, 
HEADER_NEWSGROUPS)' failed

** (pan:1889): WARNING **: Email "Re: gtk+2 themes in KDE" not sent.

(pan:1887): pan-WARNING **: Email send failed.
Check Tools|Log Viewer for more information.
Your message was saved in the folder "pan.sendlater"

Thanks