VS 2012 What Am I missing, WebClient

Public Function GetPage(ByVal url As String) As HtmlDocument ' this is me declaring the function to Get a Page, by a URL that is named in another sub
        Using webclient = New CookieAwareWebClient() ' I am going to use a CookieAwareWebClient named webclient
            Dim values = New NameValueCollection From { _   ' I am starting a NameValueCollection with 2 values
             {"ctl00_contentPlaceHolder_txtUserName", "username"}, _   ' value 1
             {"ctl00_contentPlaceHolder_txtPassword", "password"} _   ' value 2
            }    ' This is my username and password I will be using later
            webclient.UploadValues("loginURL", values)  ' Here is where I upload the information ( I am calling a POST, with automatically generated cookies ), with the values previously stated
 
            Dim html As String = webclient.DownloadString(url)   ' I am now using the URL named from another sub, to get to the page I can only dream of accessing via WebClient
            Dim doc As New HtmlDocument  ' This is an HTMLAgilityPack document
            doc.LoadHtml(html)  ' I am loading the document with my dream-based page I wish to access
            webclient.DownloadString("logoutURL")  ' I am now logging out and unlocking the page I previously accessed
            webclient.Dispose()  ' Disposing of the evidence
            Return doc  ' I am returning dream-based HTML document that I wish I could access
        End Using
    End Function