Panel to CSV to Email

Hey guys,

I am running into an issue. Basically what I am trying to do is to create an invoice and send it via email.

So I am using Ajax CalendarExtender and I do have the Toolscrkipt manager registered at the top of my page and I am using .net 4 with VS 2010.

So after a few failure I decided to export the asp:panel containing the Invoice to a CSV and then send the CSV to email. I google a few stuff and found a few codes, so this is my code for now when I hit create invoice button:

Dim SB As New StringBuilder()
        Dim SW As New StringWriter(SB)
        Dim htmlTW As New HtmlTextWriter(SW)
        pnCreateInvoice.RenderControl(htmlTW)
        Dim strOut As String = htmlTW.ToString

        Dim strCSV As String
        strCSV = tbInvoiceNumber.Text & "_" & tbClientName.Text
        For Each c In System.IO.Path.GetInvalidPathChars
            strCSV = strCSV.Replace("c", "")
        Next
        strCSV = strCSV.Replace("/", "-")

        Dim TargetFile As StreamWriter

        Try
            TargetFile = New StreamWriter("~/invoices/" & strCSV & ".csv", True)
            TargetFile.Write(htmlTW)
            TargetFile.WriteLine()
            TargetFile.Write(strOut)
            TargetFile.Close()
            lblCreateInvoiceError.Text = "Completed"
        Catch ex As Exception
            lblCreateInvoiceError.Text = ex.Message.ToString
        End Try

This is the error I get when I hit the button:

Extender control 'tbInvoiceDateCalendarExtender' is not a registered extender control. Extender controls must be registered using RegisterExtenderControl() before calling RegisterScriptDescriptors(). Parameter name: extenderControl             Description:An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.            
Exception Details: System.ArgumentException: Extender control 'tbInvoiceDateCalendarExtender' is not a registered extender control. Extender controls must be registered using RegisterExtenderControl() before calling RegisterScriptDescriptors(). Parameter name: extenderControl
Source Error:

Line 364:        Dim SW As New StringWriter(SB)
Line 365:        Dim htmlTW As New HtmlTextWriter(SW)Line 366:        pnCreateInvoice.RenderControl(htmlTW)Line 367:        Dim strOut As String = htmlTW.ToString