One domain get's not properly mapped

Well. The title is rather clear, I think...
:wink:
In my multisite install I updated the DM plugin to the latest version. That solved the problem of the revalidation.
There is 1 domain though that refuses to show the correct URL on the visitorside.
http://www.celticbuddhism.net redirects to http://celticbuddhism.webzenz.nl, where the admin URL's are all fine.

Can't figure out why.
Played with plugins. Deleted the mapping and made a new one. Placed back older DM-tables in de DB. No salvation...
This morning made a new mapping, for another domain (an .nl domain [can that be it? celticbuddhism.net is the only .net domain I have...]), went OK!

So: now I give up for a while, ask your assistence and grab myself a coffee...