If you know that the report on which you based your custom report typically offers summary options, you have either not created a sub-report for the Summary or the sub-report is not named correctly.  In order for the Summary options to be available when running the report, a Summary sub-report must exist AND it must be named “Summaries.”  Open your Report Style and check to make sure you do in fact have a sub-report for your Summaries.  If so, access the Report Tree and highlight the object that represents your sub-report.  Right click on the object and choose Rename.  Enter Summaries as the new name.  The Reporting System will not provide Summary options on a Data Feed designed for summaries if there is no sub-report named Summaries.