In order for this report to return results, you must have ports in your network which are currently unused, but had a user connected to them at one point. For example, say you're running the Reclaim Unused Up report for 30 days. In order to get results, you need to have ports with are administratively up, but unconnected. At least 31 days ago, a user must have been connected to this port, and User Tracking must have seen that user.
One of the big problems with this report is that the default UT aging timer is 30 days. So unless you've raised this, you will not be able to see results for long time periods. The best you could do would be 29 days.
