Refer to my previous post assume you want to display the sub report only data is available. therefore you can check the data for row availability and if rows are exists you can display the report. In my example we are placed our sub report in section 4 in main report. thus we can use following code to display the sub report only data is available.
if (dts.Rows.Count > 0)
Ci.ReportDefinition.Sections.SectionFormat.EnableSuppress = true;