Probleme mit Memberlist

[fishtown]

Hi,
ich habe folgende Medlung, wenn ich auf 'Das Team' klicke:

SQL ERROR [ mysqli ]

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 3 [1064]

SQL

SELECT forum_id, auth_option_id, auth_role_id, auth_setting FROM phpbb_acl_users WHERE user_id =

BACKTRACE

FILE: includes/db/mysqli.php
LINE: 163
CALL: dbal->sql_error()

FILE: includes/auth.php
LINE: 825
CALL: dbal_mysqli->sql_query()

FILE: includes/auth.php
LINE: 382
CALL: auth->acl_raw_data_single_user()

FILE: includes/auth.php
LINE: 71
CALL: auth->acl_cache()

FILE: memberlist.php
LINE: 276
CALL: auth->acl()

Woran kann das liegen? Wo muss ich den Fehler suchen?