确认.rpt文件在当前目录下,ReportSource指向报表对象实例,如
this.crystalReportViewer1.ReportSource=this.CrystalReport1
ReportDocument rd = new ReportDocument();
rd.Load(Application.StartupPath + "\\rptCancelin.rpt");
rd.SetDataSource(datatable);
crystalReportViewer1.ReportSource = rd;