Add button is not clicking/adding when adding a product

Question

Hello guyz,its me again please look at my codes and see why my add button is not adding the numbers to datagridview and i am not getting any error when i debug."it only underlines dr : SqlDataReader dr; It says "its never been used in frmNewBill" I have removed SqlDataReader dr; from the codes still the add button won't add to datagridview. Below are my codes:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.SqlClient;
namespace NSPM_Sales_Invoice {
 public partial class frmNewBill: Form {
  SqlConnection con = new SqlConnection(Properties.Settings.Default.NSPM_Sales_InvoiceCon);
  SqlCommand cmd;
  SqlDataReader dr;
  public frmNewBill() {
   InitializeComponent();
  }
  private void textBox1_TextChanged(object sender, EventArgs e) {}
  private void panel1_Paint(object sender, PaintEventArgs e) {}
  private void tableLayoutPanel1_Paint(object sender, PaintEventArgs e) {}
  private void frmNewBill_Load(object sender, EventArgs e) {
   cmbDescription.Items.Clear();
   con.Open();
   cmd = con.CreateCommand();
   cmd.CommandType = CommandType.Text;
   cmd.CommandText = "Select ProName from tbl_Products order by ProName asc";
   cmd.ExecuteNonQuery();
   DataTable dt = new DataTable();
   SqlDataAdapter da = new SqlDataAdapter(cmd);
   da.Fill(dt);
   foreach(DataRow dr in dt.Rows) {
    cmbDescription.Items.Add(dr["ProName"].ToString());
   }
   con.Close();
  }
  private void btnAdd_Click(object sender, EventArgs e) {
   if (cmbDescription.Text == "") {
    MessageBox.Show("Description is Empty");
   } else if (txtQuantity.Text == "") {
    MessageBox.Show("Quantity is Empty");
   } else if (txtUnitPrice.Text == "") {
    MessageBox.Show("Unit Price is Empty");
   } else if (txtJobNo.Text == "") {
    MessageBox.Show("JobNo is Empty");
    if (txtDeleteUpdate.Text == "") {
     int row = 0;
     dataGridView1.Rows.Add();
     row = dataGridView1.Rows.Count - 1;
     dataGridView1["Description", row].Value = cmbDescription.Text;
     dataGridView1["Quantity", row].Value = txtQuantity.Text;
     dataGridView1["UnitPrice", row].Value = txtUnitPrice.Text;
     dataGridView1["Value", row].Value = txtValue.Text;
     dataGridView1["JobNo", row].Value = txtJobNo.Text;
     dataGridView1.Refresh();
     cmbDescription.Focus();
     if (dataGridView1.Rows.Count > 0) {
      dataGridView1.CurrentCell = dataGridView1.Rows[dataGridView1.Rows.Count - 1].Cells[1];
     }
    } else {
     int i = 0;
     DataGridViewRow row = dataGridView1.Rows[i];
     row.Cells[1].Value = cmbDescription.Text;
     row.Cells[2].Value = txtQuantity.Text;
     row.Cells[3].Value = txtUnitPrice.Text;
     row.Cells[4].Value = txtValue.Text;
    }
    cmbDescription.Text = "";
    txtQuantity.Text = "";
    txtUnitPrice.Text = "";
    txtValue.Text = "";
    txtJobNo.Text = "";
   }
  }
  private void dataGridView1_RowPostPaint(object sender, DataGridViewRowPostPaintEventArgs e) {
   this.dataGridView1.Rows[e.RowIndex].Cells[0].Value = (e.RowIndex + 1).ToString();
  }
  int i;
  private void dataGridView1_CellDoubleClick(object sender, DataGridViewCellEventArgs e) {
   i = e.RowIndex;
   DataGridViewRow row = dataGridView1.Rows[i];
   cmbDescription.Text = row.Cells[1].Value.ToString();
   txtQuantity.Text = row.Cells[2].Value.ToString();
   txtUnitPrice.Text = row.Cells[3].Value.ToString();
   txtValue.Text = row.Cells[4].Value.ToString();
   txtDeleteUpdate.Text = row.Cells[0].Value.ToString();
  }
  private void btnDelete_Click(object sender, EventArgs e) {
   if (txtDeleteUpdate.Text == "") {
    MessageBox.Show("Select Product to Delete");
   } else {
    foreach(DataGridViewRow row in dataGridView1.SelectedRows) {
     if (!row.IsNewRow) dataGridView1.Rows.Remove(row);
    }
   }
  }
 }
}

please help its urgently needed. thanks