How to not be anonymous

I hate pestering you guys with trivia, but here goes again.

Every time I set up a new mtn database I end up with trouble.  Always 
it's different trouble.  I don't seem to remember all the details from 
previous times, and I seem to misread the manual again and again.

THis time what's stymied me is anonymity.

I.m trying to populate a database by pulling form an usher server:


hendrik@notlookedfor:~/monotone$ mtn --key [email protected] pull mtn://topoi.pooq.com/slides?com.pooq.hendrik.slides --db ~/monotone/slides.db
mtn: connecting to 'mtn://topoi.pooq.com/slides'
mtn:   include pattern  'com.pooq.hendrik.slides'
mtn:   exclude pattern  ''
mtn: finding items to synchronize:
mtn: warning: protocol error while processing peer mtn://topoi.pooq.com/slides: 'received network error: anonymous access to branch 'com.pooq.hendrik.slides' denied by server'
mtn:  bytes in | bytes out | certs in
mtn:        97 |       350 |        0
mtn: error: processing failure while talking to peer 'mtn://topoi.pooq.com/slides', disconnecting
hendrik@notlookedfor:~/monotone$ 

now, I have the proper permissions to read that remote data base.  
But what do I have to do to be recognised as not being anonymous?
Is  specifying the key with --key [email protected] not enough?

-- hendrik