can not delete w. POP3

[BORGULYA Gergely]

If any user tries to delete one's mail from a POP3 mailserver with IMP,
the following warning appears:

Warning: Wrong parameter count for imap_delete() in /opt/horde/imp/mailbox.php3 on line 142

Warning: Cannot add more header information - the header was already sent (header information may be added
only before any output is generated from the script - check for text or whitespace outside PHP tags, or calls to
functions that output text) in ./templates/doctype.inc on line 8

The mail leaves undeleted.

my system parameters are:
IMP webserver (under my control):
- SuSE Linux 6.4
- PostgreSQL 6.5.3.
- Apache
POP3 server 
- I have not much idea, I'm only a user
- Sun Ultra-Enterprose 4000 system

Is it a standard misconfiguration error whitch I couldn't find in the FAQ, or
something more complex?

BORGULYA, Gergely