[otrs] LDAP and Address Book, customers are displayed with username, full name, email address and username again

Hi all, I have a short and maybe simple question. We have set our OTRS 3.0.4 up to authenticate the users and agents with LDAP (Active Directory 2003) and that's working great! The only annoying thing now is that when I reply or forward an email and I type in the first two letters of a name many customers are displayed (that's OK, we have a lot of users), but the users aren't displayed with username and or email address but with username, full name, email address and username again, so for example when I type in "Er" I get myself as customer and it is displayed as ""ErikA Erik van Ast" (ErikA)". How can I make that change so only the username and the email address or only the full name and the email address are visible? Met vriendelijke groet / Kind regards / Mit freundlichem Gruß, Erik van Ast