protected void ddCourse_SelectedIndexChanged(object sender, EventArgs e) { if (ddCourse.SelectedIndex > 0) { int Admission_Year_ID = Convert.ToInt32(ddCourse.SelectedValue); clsStudent stud = new clsStudent(); DataSet ds = stud.listClassIDbyAdmissionProgramme(Admission_Year_ID); drp_ClassID.DataSource = ds.Tables[0]; drp_ClassID.DataTextField = "Class_Name"; drp_ClassID.DataValueField = "Class_ID"; drp_ClassID.DataBind(); drp_ClassID.Items.Insert(0, new ListItem("Select One", "-1")); } }