[Juser] Error 406: not-acceptable

[deckrider+juser]

Hi,

I created a conference:  summitscene.org at conference.jabber.org.

All is good, except when I try to invite someone, I get this:

Error 406: not-acceptable

Oddly, when I create a new conference with the same settings, I don't
have this problem, but how do I get the original conference fixed?

I'm using Gajim 0.11.1 for all the above.

Thanks,
Deck.