Postgres - Error when creating an album

Issue Summary

I get the following just after creating a new album.

* warning: pg_query() [function.pg-query]: Query failed: ERROR: null value in column "id" violates not-null constraint in /home/alan/dev/cf.ou/includes/database.pgsql.inc on line 138.
* user warning: query: INSERT INTO x_album_ac (id, nid, updateid) VALUES (null, 22, 1) in /home/alan/dev/cf.ou/sites/all/modules/photos_access/photos_access.module on line 208.

I presume this is some difference between the way that Mysql and Postgres handle automatic creation of id's in sequence - but not sure what.