You probably want to move this to the Netflow Traffic Analyzer forum or Report Lab forum.
The SQL query is cut off on the right in your screenshot. It looks like the DateTime column is present in multiple tables involved in the query. If you change it to
( NetflowApplicationSummary.DateTime > (GetDate()-30) )
it should work.
If you are running NTA v4, you should be able to design this in the web based reports as opposed to the legacy report writer on the NTA server.
Thanks so much, that was it. Like I said, I'm very new to this, so your post helped me better understand how SQL Queries are written.
In the future I will post threads like this in the Netflow Traffic Analyzer forum.