DataMapper ORM v1.8.2

[eluser]North2Alaska[/eluser]
I'm just starting to use DM. I've created a simple model to query a table, but I want to add a prefix. My tables have multiple prefixes and I will have to define the prefix for each table/class.

class User extends DataMapper {

var $prefix = "auth_";

My problem is the prefix is not honored.

A Database Error Occurred
Error Number: 1146
Table 'publisher.users' doesn't exist
DESCRIBE `users`
Filename: /Library/WebServer/Documents/ci/libraries/Datamapper.php
Line Number: 645

I can get things to work for this simple test if I set the prefix in the config file, but obviously won't work for the other prefixes. I'm sure I'm doing something simple, but just can see it. Any ideas?