VB.NET ช่วยดูโค้ดให้ทีครับพี่ๆ ExecuteNonQuery: Connection property has not been initialized

Dim sqlAdd As String
            Dim i As Integer = 0
            For i = 0 To ListView1.Items.Count - 1
                sb = New StringBuilder
                sb.Append("INSERT  INTO Purchase_Order(Num_ID, Sell_Name, Buy_Address, Buy_Tel, Buy_Paid, dtp_Due, Buy_Fax, dtp_Dalivery, Buy_Con, ProID, ProName, ProPrice, Qty, Price, Discount, Total, Vat, Net, Msn)")
                sb.Append(" VALUES(@Num_ID, @Sell_Name, @Buy_Address, @Buy_Tel, @Buy_Paid, @dtp_Due, @Buy_Fax, @dtp_Dalivery, @Buy_Con, @ProID, @ProName, @ProPrice, @Qty, @Price, @Discount, @Total, @Vat, @Net, @Msn)")
                sqlAdd = sb.ToString
                exeCommand = New SqlCommand
                With exeCommand
                    .CommandText = sqlAdd
                    .Connection = conn
                    .Parameters.Add("@Num_ID", SqlDbType.NVarChar).Value = txtNum_ID.Text.Trim
                    .Parameters.Add("@Sell_Name", SqlDbType.NVarChar).Value = txtSell_Name.Text.Trim
                    .Parameters.Add("@Buy_Address", SqlDbType.NVarChar).Value = txtBuy_Address.Text.Trim
                    .Parameters.Add("@Buy_Tel", SqlDbType.Int).Value = txtBuy_Tel.Text.Trim
                    .Parameters.Add("@Buy_Paid", SqlDbType.NVarChar).Value = txtBuy_Paid.Text.Trim
                    .Parameters.Add("@dtp_Due", SqlDbType.DateTime).Value = dtp_Due.Value()
                    .Parameters.Add("@Buy_Fax", SqlDbType.Int).Value = txtBuy_Fax.Text.Trim
                    .Parameters.Add("@dtp_Dalivery", SqlDbType.DateTime).Value = dtp_Dalivery.Value()
                    .Parameters.Add("@Buy_Con", SqlDbType.NVarChar).Value = txtBuy_Con.Text.Trim
                    .Parameters.Add("@ProID", SqlDbType.NVarChar).Value = ListView1.Items(i).SubItems(1).Text
                    .Parameters.Add("@ProName", SqlDbType.NVarChar).Value = ListView1.Items(i).SubItems(2).Text
                    .Parameters.Add("@ProPrice", SqlDbType.Float).Value = ListView1.Items(i).SubItems(3).Text
                    .Parameters.Add("@Qty", SqlDbType.Int).Value = ListView1.Items(i).SubItems(4).Text
                    .Parameters.Add("@Price", SqlDbType.Float).Value = ListView1.Items(i).SubItems(5).Text
                    .Parameters.Add("@Discount", SqlDbType.Float).Value = ListView1.Items(i).SubItems(6).Text
                    .Parameters.Add("@Total", SqlDbType.Float).Value = ListView1.Items(i).SubItems(7).Text
                    .Parameters.Add("@Vat", SqlDbType.Float).Value = ListView1.Items(i).SubItems(8).Text
                    .Parameters.Add("@Net", SqlDbType.Float).Value = ListView1.Items(i).SubItems(9).Text
                    .Parameters.Add("@Msn", SqlDbType.NVarChar).Value = ListView1.Items(i).SubItems(10).Text
                    .ExecuteNonQuery() '--มันมีปัญหาตรงเนี่ยครับ--
                End With