uc_order ignoring $db_prefix overrides.

I have two uberCart instillation that I would like to configure the sharing of orders/payments tables via a $db_prefix override in the settings.php. I have installed the module, and the installation used the overrides so that the tables were not created. when when I go to /admin/store/orders I get warnings that the tables that were (rightly) not created don't exist, and none of the orders for the shared tables show up.