[otrs] PostmasterPOP3 error: Can't use string ("mail") as an ARRAY

Dear list, Maybe someone knows the answer to my problem. The situation: OS: CentOS OTRS: Version 2.2.1 + ITSM 1.0.1 The postmaster account is setup succesfully and username and password is working. Manually running the postmasterpop3 (./PostmasterPOP.pl) gives the following error: "Can't use string ("mail") as an ARRAY ref while "strict refs" in use at /opt/otrs/Kernel/System/CustomerUser/LDAP.pm line 240, <DATA> line 225." Couldn't find anything wrong in LDAP.pm Please help me out :) Kind Regards, Jeroen Prinse.