[otrs] Issue with autoreply on new ticket

I'm running a setup of OTRS 1.3.2, which is generally working as supposed to, but there's one issue which prohibits it from being rolled out as a production system for the helpdesk I operate. All new tickets to the two queues get processed (tickets created) and I get a notification about new tickets, but the clients don't get their autoresponses. The log indicates that they are even't processed, despite they should be. The autoresponders have been assigned to the appropriate queues, but no cigar. What could be wrong? Or could this be a bug? Thanks in advance for any hints or solutions! Rasbelin