Transaction and cascade problem

Hi All,

I have postgres 7.1 set up with two tables (groups, users). groups has 2 columns name, groupid where id is the primary key autoincrement and name is unique. users has 3 columns name, userid, groupid. I have a constraint on users which says that groupid must exists in the group table. I also have a cascade delete on the groups table to delete any users that are in the group I am removing. I regular (no transaction) mode everything works fine. When I start a transaction and I add a group to the group table, then delete it before a commit or rollback I get the following error:

ERROR: triggered data change violation on relation "groups"

After that the transaction must be rolledback. Any clues?

Thanks

Glenn