มีปัญหาเรื่องการ Try...Catch ครับ รบกวนท่านผู้รู้ด้วยครับ

if (myCon.State == ConnectionState.Open)
            {
                myCon.Close();
            }
            myCon.Open();

Protected Sub cmdISave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdISave.Click
        If txtInvoiceDate.Text = "" Then
            MsgBox("กรุณาใส่วันที่ก่อน", MsgBoxStyle.OkOnly)
            Exit Sub
        
        Else
            If (txtInvoiceNo.Text = "") Then
                ' New Invocie
                Dim SQL As String

                mySqlCon.Open()

                SQL = "SELECT Value FROM RunningNumber WHERE Name = 'InvoiceNo'"

                mySqlCmd = New SqlCommand(SQL, mySqlCon)
                Try

                    mySqlReader = mySqlCmd.ExecuteReader
                    While mySqlReader.Read
                        txtInvoiceNo.Text = "INV" & Format(mySqlReader.Item(0), "000") & "/" & Year(Today)
                    End While
                    mySqlReader.Close()

                Catch ex As Exception
                    MsgBox(ex.Message)
                    Exit Sub
                End Try

                Try
                    Dim strInvoiceNo As String
                    strInvoiceNo = txtInvoiceNo.Text
                    Dim BCDate As String
                    BCDate = txtInvoiceDate.Text.Substring(0, txtInvoiceDate.Text.Length - 4) & CStr(CInt(txtInvoiceDate.Text.Substring(txtInvoiceDate.Text.Length - 4)) - 543)


                    SQL = "INSERT INTO Invoice (InvoiceNo, InvoiceDate, CustomerCode, TotalAmount, VAT, AmountDue) " & _
                          " VALUES ('" & strInvoiceNo & "',convert(datetime,'" & BCDate & "',103), '" & txtCustomerCode.Text & "' , " & _
                          " '" & Format(txtTotalAmount.Text, "General Number") & "','" & Format(txtVAT.Text, "General Number") & "','" & Format(txtAmountDue.Text, "General Number") & "')"

                    mySqlCmd = New SqlCommand(SQL, mySqlCon)
                    mySqlCmd.ExecuteNonQuery()

                    Dim i As Integer
                    For i = 1 To row_coll.Count


                        SQL = "INSERT INTO InvoiceLineItem (InvoiceNo, LineItemNo, ProductCode, ProductName, Quantity, UnitPrice, Units, ExtendedPrice) " & _
                              " VALUES ('" & strInvoiceNo & "','" & i & "'," & _
                              "'" & row_coll.Item(i).item(2) & "'," & _
                              "'" & row_coll.Item(i).item(3) & "'," & _
                              "'" & Format(row_coll.Item(i).item(4), "General Number") & "'," & _
                              "'" & Format(row_coll.Item(i).item(5), "General Number") & "'," & _
                              "'" & row_coll.Item(i).item(6) & "'," & _
                              "'" & Format(row_coll.Item(i).item(7), "General Number") & "')"
                        mySqlCmd = New SqlCommand(SQL, mySqlCon)
                        mySqlCmd.ExecuteNonQuery()
                    Next

                    SQL = "UPDATE RunningNumber SET Value = Value + 1 WHERE Name = 'InvoiceNo'"
                    mySqlCmd = New SqlCommand(SQL, mySqlCon)
                    mySqlCmd.ExecuteNonQuery()

                    UnSetEditMode()

                    MsgBox("บันทึกเรียบร้อยแล้ว", MsgBoxStyle.OkOnly)

                Catch ex As Exception
                    MsgBox(ex.Message)
                End Try

                mySqlCon.Close()

            Else
                Dim SQL As String
                mySqlCon.Open()

                Try
                    Dim BCDate As String
                    BCDate = txtInvoiceDate.Text.Substring(0, txtInvoiceDate.Text.Length - 4) & CStr(CInt(txtInvoiceDate.Text.Substring(txtInvoiceDate.Text.Length - 4)) - 543)
                    SQL = "UPDATE Invoice SET InvoiceDate = Convert(Datetime,'" & BCDate & "',103) " & _
                          " ,TotalAmount = '" & Format(txtTotalAmount.Text, "General Number") & "' " & _
                          " ,CustomerCode = '" & txtCustomerCode.Text & "' " & _
                          " ,VAT = '" & Format(txtVAT.Text, "General Number") & "' " & _
                          " ,AmountDue = '" & Format(txtAmountDue.Text, "General Number") & "' " & _
                          "WHERE InvoiceNo = '" & txtInvoiceNo.Text & "'"
                    mySqlCmd = New SqlCommand(SQL, mySqlCon)
                    mySqlCmd.ExecuteNonQuery()

                    SQL = "DELETE FROM InvoiceLineItem WHERE InvoiceNo = '" & txtInvoiceNo.Text & "'"
                    mySqlCmd = New SqlCommand(SQL, mySqlCon)
                    mySqlCmd.ExecuteNonQuery()

                    Dim i As Integer
                    For i = 1 To row_coll.Count
                        SQL = "INSERT INTO InvoiceLineItem (InvoiceNo, LineItemNo, ProductCode, ProductName, Quantity, UnitPrice, Units, ExtendedPrice) " & _
                              " VALUES ('" & txtInvoiceNo.Text & "','" & i & "'," & _
                              "'" & row_coll.Item(i).item(2) & "'," & _
                              "'" & row_coll.Item(i).item(3) & "'," & _
                              "'" & Format(row_coll.Item(i).item(4), "General Number") & "'," & _
                              "'" & Format(row_coll.Item(i).item(5), "General Number") & "'," & _
                               "'" & row_coll.Item(i).item(6) & "'," & _
                              "'" & Format(row_coll.Item(i).item(7), "General Number") & "')"
                        mySqlCmd = New SqlCommand(SQL, mySqlCon)
                        mySqlCmd.ExecuteNonQuery()
                    Next

                    UnSetEditMode()

                    MsgBox("บันทึกเรียบร้อยแล้ว", MsgBoxStyle.OkOnly)

                Catch ex As Exception
                    MsgBox(ex.Message)
                End Try

                mySqlCon.Close()
            End If
        End If

    End Sub