[repost] why this code not working

cmd.CommandType = CommandType.Text;
                 cmd.Connection = sqlcon;
                 cmd.CommandText = "INSERT INTO TBL_Customers (customer_name,FK_fk_id,commissary,FK_area_id,customer_address,tel1,tel2
,id_number,datebirth,tel4) VALUES (@customer_name,@FK_fk_id,@commissary,@FK_area_id,@customer_address,@tel1,@tel2,@id_number,@datebirth,@tel4)";
                 cmd.Parameters.AddWithValue("@customer_name", txtname.Text);
                 cmd.Parameters.AddWithValue("@FK_fk_id", comboCategoryCustomers.ValueMember);
                 cmd.Parameters.AddWithValue("@commissary", txtcommissary.Text);
                 cmd.Parameters.AddWithValue("@FK_area_id", comboAreaCustomer.ValueMember);
                 cmd.Parameters.AddWithValue("@customer_address", txtcustomer_address.Text);
                 cmd.Parameters.AddWithValue("@tel1", txttel1.Text);
                 cmd.Parameters.AddWithValue("@tel2", txttel2.Text);
                 cmd.Parameters.AddWithValue("@id_number", txtid_number.Text);
                 cmd.Parameters.AddWithValue("@datebirth", this.dateTimePicker1datebirth);
                 cmd.Parameters.AddWithValue("@tel4", txttel4.Text);




                 sqlcon.Open();
                 cmd.ExecuteNonQuery();

                 MessageBox.Show("Saved");
                 sqlcon.Close();