Sendxmpp 503 error

Hey guys,

I recently installed ejabberd 2.0.5 on a debian lenny server. I can use the service without troubles via Miranda IM. Today I wanted to migrate some perl scripts to use the ejabberd server but it won't work. The software in use is sendxmpp (http://sendxmpp.platon.sk/). The script tells me that the service is unavailable (503) and my searches didn't lead anywhere.

Anybody got an idea about what might be wrong here ?