protected void ddPerson_SelectedIndexChanged(object sender, EventArgs e) { ComposeDAL sdal = new ComposeDAL(); if (ddPerson.SelectedValue == "-1") { ddReciever.Items.Clear(); } else if (ddPerson.SelectedValue == "Admin") { ddReciever.Items.Clear(); ddReciever.Enabled = false; } else if (ddPerson.SelectedValue == "-3") { int id = Convert.ToInt32(Session["Marks_Key"]); ddReciever.DataSource = sdal.GetStudentNameByCourse(id); ddReciever.DataTextField = "Student Name"; ddReciever.DataValueField = "Student Name"; ddReciever.DataBind(); } else { //label error here } }