You need to go into rule_values table in database and make sure this : Mercs:AllowMercs is set to "true" Also, you need make sure the "class" on all the merc merchant npc's are set to "71". If you know how to run queries in the database, it's an easy task by running this:
Code:
UPDATE npc_types SET class = 71 WHERE lastname LIKE '%Mercenary Liaison';