How are the agents determined in your work flow? The work flow could be defined to use your company’s HR structure, a defined organizational structure, a job, a position or a defined work center as the agent. Based on the limited description of your problem, I would guess that you are using a work center that includes the users that perform a specific task. If this is the case make sure the employee number, position number or job title of the user who is complaining is not included in the work center.
Tools -> Business Workflow -> Expert Mode
PO10 – Organizational Unit
PO03 – Job
PO13 – Position
PO01 – Work center