Load Report Failed.

Below code is working fine
CrystalDecisions.CrystalReports.Engine.ReportDocument rp;
string reportPath = Server.MapPath("LogReport.rpt");

rp = new CrystalDecisions.CrystalReports.Engine.ReportDocument();

sql = "Select 'User Name :'+lmaster.l_name as username,'' as sno, userdetail.user_ip as uip from userdetail order by servertime";

dsmain = mydata.GetDataSet(sql, 1);// this method my own method will be return query data in dataset.
rp.FileName = reportPath;
rp.SetDataSource(dsmain.Tables[0]);
crviewer.ReportSource = rp;