DataTable dt = "DataTable with some data";TrackTime tt = TrackTime(); //Master report with subreport 'SubTrackTime'if (dt != null){ Telerik.Reporting.SubReport subReport = tt.Items.Find("subReport", true)[0] as Telerik.Reporting.SubReport; SubTrackTime stt = (SubTrackTime)subReport.ReportSource; Telerik.Reporting.Table tbl2 = stt.Items.Find("detailTable", true)[0] as Telerik.Reporting.Table; tbl2.DataSource = "DataTable with some data"; Telerik.Reporting.Table tbl = tt.Items.Find("timeTable", true)[0] as Telerik.Reporting.Table; tbl.DataSource = dt; rvTimeTrack.Report = tt; //rvTimeTrack - reportViewer}