AsynchFileUpload not working

I have the following control on my asp.net web page and I cannot get the selected file to upload.  Below the control is the code-behind and it does not even appear to throw an error unless I remove the try...catch block then it throws an error of "The given path's format is not supported."  I tried it both normally and inside an UpdatePanel and neither is working.  Can anyone give guideance?  Thanks.

Here is example of textbox contents.

\\server\apps\shareddocs\Photos\Crucius, Kim\RO45945

    <asp:AsyncFileUpload ID="AsyncFileUpload1" runat="server"
        UploaderStyle="Modern" onclientuploadcomplete="showConfirmation" />

    Protected Sub UploadedComplete(ByVal sender As Object, ByVal e As AjaxControlToolkit.AsyncFileUploadEventArgs) Handles AsyncFileUpload1.UploadedComplete
        Dim filePath As String = txtFolderPath.Text & "\" & AsyncFileUpload1.PostedFile.FileName
        Try
            AsyncFileUpload1.SaveAs(filePath)

        Catch ex As Exception
            Label2.Text = filePath & "could not be uploaded " & ex.Message
            Exit Sub

        End Try
    End Sub