[Solved] Search record in ASP.Net GridView using TextBox on Button Click not working

How to add search function using C#. My search function not working.

please help

namespace MUNP_SMS_SYSTEM
{
    public partial class WebForm2 : System.Web.UI.Page
    {
        protected int selectedIndex = 0;
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!this.IsPostBack)
            {
                this.BindGrid();
            }

        }
        private void BindGrid()
        {
            string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
            using (SqlConnection con = new SqlConnection(constr))
            {
                using (SqlCommand cmd = new SqlCommand("SELECT EmpCode, EmpName, Mobile, EmailID FROM tbl_Employees"))
                {
                    using (SqlDataAdapter sda = new SqlDataAdapter())
                    {
                        cmd.Connection = con;
                        sda.SelectCommand = cmd;
                        using (DataTable dt = new DataTable())
                        {
                            sda.Fill(dt);
                            GridView1.DataSource = dt;
                            GridView1.DataBind();
                        }
                    }
                }
            }
        }
        protected void OnPageIndexChanging(object sender, GridViewPageEventArgs e)
        {
            GridView1.PageIndex = e.NewPageIndex;
            this.BindGrid();
        }
        protected void btnSearch_Click(object sender, EventArgs e)
        {
            BindGridView(TextBox1.Text);
        }
        private void BindGridView(string searchVal)
        {
            SqlConnection con = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["constr"].ToString());
            try
            {
                DataTable objdt = new DataTable();
                string query = searchVal == "" ? "select * from tbl_Employees;" : "select * from tbl_Employees where EmpCode like '%" + searchVal + "%';";
                SqlDataAdapter da = new SqlDataAdapter(query, con);
                con.Open();
                da.Fill(objdt);
                con.Close();
                if (objdt.Rows.Count > 0)
                {
                    GridView1.DataSource = objdt;
                    GridView1.DataBind();
                }
            }
            catch
            {
                con.Close();
            }
        }
    }
}