Database Error while listing messages

Hi,

While building message list, I get this error :

PDOException : SQLSTATE[42883]: Undefined function: 7 ERROR: operator does not exist: character varying = bigint LINE 32: (g.uid = u.uid AND u.uid!= 0) OR (u.uid = 0 AND g.ui... ^ HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts.: SELECT u.name as name, g.uid as uid, g.message as message, g.TIMESTAMP as timestamp FROM ( SELECT uid, message, TIMESTAMP FROM ( ( SELECT m1.uid1 AS uid, m1.timestamp AS TIMESTAMP, m1.message AS message FROM {drupalchat_msg} m1 INNER JOIN ( SELECT MAX( t1.timestamp ) AS TIMESTAMP, t1.uid1 FROM {drupalchat_msg} t1 WHERE t1.uid2 = :uid GROUP BY t1.uid1 ) recent ON recent.timestamp = m1.timestamp AND recent.uid1 = m1.uid1 ORDER BY TIMESTAMP DESC ) UNION ( SELECT m1.uid2 AS uid, m1.timestamp AS TIMESTAMP, m1.message AS message FROM {drupalchat_msg} m1 INNER JOIN ( SELECT MAX( t1.timestamp ) AS TIMESTAMP, t1.uid2 FROM {drupalchat_msg} t1 WHERE t1.uid1 = :uid GROUP BY t1.uid2 )recent ON recent.timestamp = m1.timestamp AND recent.uid2 = m1.uid2 ORDER BY TIMESTAMP DESC ) ) AS f ORDER BY 3 DESC ) AS g INNER JOIN {drupalchat_users} u ON (g.uid = u.uid AND u.uid!= 0) OR (u.uid = 0 AND g.uid = CONCAT('0-', u.session)) GROUP BY uid; Array ( [:uid] => 1 ) dans drupalchat_get_messages() (ligne 1119 dans /home/oturpin/equidrup/sites/all/modules/drupalchat/drupalchat.module).

Database is postgres 8.4

Thx for any feedback !