my nntp messages are accepted but do not reach the groups

Hello,

I tried to post some messages earlier today, but while they are accepted
by gmane, they do not make it to the groups.

First one was to gmane.emacs.gnus.general, and then as it didn't appear
there I used gmane.test for... some tests :-)

But none of my nntp messages are there.

Then I tried via mail, and there it reaches the group.

I modified my mail-host-address because gnus complained about strange
message-ids, but apart from gnus not complaining anymore, it didn't
change the outcome: my messages still do not appear on the test group.

What can I do to diagnose this ?

Thanks,
-- 
Rémi