SQL Error in Admin UI

Using Drupal 6.14 with OG 6.x-2.0 and OG Mandatory Groups 6.x-1.3, go to the
OG Mandatory Groups Admin UI.

Problems:
- Under "Assign Groups" there are no groups to choose from, although there are
a couple of OG groups defined in the DB
- Under "Available Groups", the list is empty, and the following error displays:

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* user warning: Unknown column 'o.selective' in 'where clause' query: SELECT n.nid, n.title, o.* FROM node n INNER JOIN og o ON n.nid = o.nid WHERE (o.selective = 3 OR o.selective = 0) ORDER BY n.title in /var/www/taubenschlag/modules/og_multiple_mandatory_groups_by_role/og_multiple_mandatory_groups_by_role.module on line 645.
* warning: Invalid argument supplied for foreach() in /includes/form.inc on line 1428.

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Hope the above mekes sense; am quite new to Drupal.

Thanks for looking into this!