remove agents from report when they have not logged in during the time period

Summary

We have a report that shows logins, duration, and average for agents, but we don't want to see agents who have not logged in

Content

I am having an issue with a report where we have a filter that says date_diff(user_trans.end_dttm,user_trans.start_dttm) > 0 but no matter what I do, I am getting agents who have and have not logged in during the time frame of the report.  So for example, I am running it for today only.  Only 12 agents have logged in today but I am getting 55 agents in the report.  I also tried to add to_number to the beginning of that formula, but that did not help.