ExecuteScalar requires an open and available Connection. The connections current state is closed.

ExecuteScalar requires an open and available Connection. The connection's current state is closed.

this error raised

namespace ITS_Group{    public partial class Login : System.Web.UI.Page    {
        private DataTable GetData(SqlCommand cmd)        {
            DataTable dt = new DataTable();
            String strConnString = System.Configuration.ConfigurationManager.ConnectionStrings[1].ConnectionString;
            SqlConnection con = new SqlConnection(strConnString);
            SqlDataAdapter sda = new SqlDataAdapter();
            cmd.CommandType = CommandType.Text;            cmd.Connection = con;
            try            {                con.Open();
                sda.SelectCommand = cmd;                sda.Fill(dt);
                return dt;            }            catch (Exception ex)
            {                Response.Write(ex.Message);
                return null;            }            finally            {
                //con.Close();                sda.Dispose();
                con.Dispose();            }        }

protected void btn_login_Click(object sender, EventArgs e)        {
lblMsg.Text = "";
            SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings[1].ConnectionString);
            SqlCommand cmd = new SqlCommand("select COUNT(*)FROM Users WHERE User_Name=@User_Name and Password=@Password");
            cmd.Parameters.AddWithValue("@User_Name", txt_userName.Text.Trim());
            cmd.Parameters.AddWithValue("@Password", txt_password.Text.Trim());
            DataTable dt = GetData(cmd);
            int OBJ = Convert.ToInt32(cmd.ExecuteScalar());
            if (OBJ > 0)            {
                Session["User_Name"] = txt_userName.Text;
                Response.Redirect("Default.aspx");            }else            {
                lblMsg.Text = "User Name/Password incorrect";            }
        }