roster nicknames with transports

Hi Again.

When I register to the icq transport (pyicqt) on my ejabberd server, all my icq contacts are added to my roster, but with their icq number instead of their nickname.
However, when I look at the pyicqt xml spool file, I can see the nickname of my contacts.
When I rename a contact in my roster, queries are sent to the ejabberd server, and I can see that the ejabberd spool file : "roster.DCD" changes.
Shouldn't the transport perform thoses queries, and also update the roster.DCD file when I register to it ?

I experienced this pb with gajim and psi. I think the problem is on the server side, but I don't know if ejabberd or the transport, or both are responsible for that.
Is it possible that some modules I use are in conflict ?

Thanks