I am using sap crystal report binding crystal report to CrystalReporterViewer than its displaying error Object or Instance reference not set

i am able to fetch record from db based on id but error is here

ReportDocument rpt = new ReportDocument();
CrystalReport1 cry = new CrystalReport1();
cry.SetDataSource(_ds); //error "Invalid file path"
OR
rpt .SetDataSource(_ds); //error "Invalid file path"
crystalReportViewer1.ReportSource = _ds.Tables[0];
crystalReportViewer1.Refresh();