Nested query issue in reports

As i created nested queries in report and but i didnt get the

When troubleshooting anything involving datasources in a report, the first thing is to check the right column of the Preview tab. This shows the data that's coming back, in XML format. If the data is correct in the XML, the problem is in your report design, often in associating datakeys with components. If the data is incorrect or missing, either there's an issue with your datasource setup or you need to try again without the preview limit.

Have you solved this problem? How does the structure of the Flow subquery looks like and the internal sub query as well? Can you share a screenshot of that as well?