Try this:
rptStudyCertificate rsc = new rptStudyCertificate();
CrystalReportViewer1 = new CrystalReportViewer();
using (DataClasseDataContext db = new DataClasseDataContext())
{
var list = (from data in db.StudyCertificates
join clsdet in db.StudentClassDetails on data.AdmissionNo equals clsdet.AdmissionNo
where data.ID == Convert.ToInt16(sno)
select new { ID = data.ID, Class = clsdet.Class, AcademicYear =
clsdet.AcademicYear, AdmissionNo =
clsdet.AdmissionNo, Conduct = data.Conduct}).ToList();
if (list != null)
{
rsc.SetDataSource(list);
CrystalReportViewer1.ReportSource = rsc;
}
}