i have the latest versions of the project module and og project running on postgresql 8.1

and get this error:

* warning: pg_query() [function.pg-query]: Query failed: ERROR: syntax error at or near "ON" at character 24 in /var/www/virtual/alarmix.de/qm/htdocs/includes/database.pgsql.inc on line 125.
* user warning: query: SELECT COUNT( DISTINCT ON (n.nid) n.nid) FROM node n INNER JOIN project_issues p ON p.nid = n.nid INNER JOIN node_revisions r ON r.vid = n.vid INNER JOIN users u ON p.assigned = u.uid WHERE n.status = 1 AND ((p.sid = '1' OR p.sid = '2' OR p.sid = '4')) in /var/www/virtual/alarmix.de/qm/htdocs/includes/database.pgsql.inc on line 144.
* warning: pg_query() [function.pg-query]: Query failed: ERROR: SELECT DISTINCT ON expressions must match initial ORDER BY expressions in /var/www/virtual/alarmix.de/qm/htdocs/includes/database.pgsql.inc on line 125.
* user warning: query: SELECT DISTINCT ON (n.nid) n.nid FROM node n INNER JOIN project_issues p ON p.nid = n.nid INNER JOIN node_revisions r ON r.vid = n.vid INNER JOIN users u ON p.assigned = u.uid WHERE n.status = 1 AND ((p.sid = '1' OR p.sid = '2' OR p.sid = '4')) ORDER BY n.changed DESC LIMIT 20 OFFSET 0 in /var/www/virtual/alarmix.de/qm/htdocs/includes/database.pgsql.inc on line 144.