asterisk users - Dec 2010 - Asterisk 1.6 iax auth rsa failed with policie not found

Hi,

I had 2 Asterisk servers connected together in iax with auth=rsa and 
proper keys for user and peer in each direction. It worked well till I 
upgraded one of them to Asterisk 1.6.13 Since I get "No authority
found"

I thought that problem came from keys as the server with 1.6.13 was 
changed in the mean time, so I regenerated both keys on each server and 
copy the public of each one to the other: problem stays.

What am I missing? What changes in 1.6 where made concerning this matter?

Thanks for any hint.

-- 
Daniel