VB:NET "Object reference not set to an instance of an object." in a Net.WebResponse variable - vb.net

Question

in the following code i am trying to handle different server resposes:
this function is used to read xml or html soruce from a web page
and in the commented line i get "Object reference not set to an instance of an object."
i wonder why.
Public Function GetPageHTML(ByVal URL As String, _
Optional ByVal TimeoutSeconds As Integer = 10) _
As String
' Retrieves the HTML from the specified URL,
' using a default timeout of 10 seconds
Dim objRequest As Net.WebRequest
Dim objResponse As Net.WebResponse
Dim objStreamReceive As System.IO.Stream
Dim objEncoding As System.Text.Encoding
Dim objStreamRead As System.IO.StreamReader
Try
' Setup our Web request
objRequest = Net.WebRequest.Create(URL)
objRequest.Timeout = TimeoutSeconds * 1000
' Retrieve data from request
Select Case CType(objResponse, Net.HttpWebResponse).StatusCode 'Here is where i get the error Object reference not set to an instance of an object.
Case Net.HttpStatusCode.InternalServerError
'This is sloppy, but a quick example for one of your sub-questions.
System.Threading.Thread.Sleep(10000)
'Try again.
objResponse = objRequest.GetResponse
Case Net.HttpStatusCode.BadRequest
'Error Handling
Case Net.HttpStatusCode.OK
'Proceed as normal.
Case Else
'Error Handling
End Select
objStreamReceive = objResponse.GetResponseStream
objEncoding = System.Text.Encoding.GetEncoding( _
"utf-8")
objStreamRead = New System.IO.StreamReader( _
objStreamReceive, objEncoding)
' Set function return value
GetPageHTML = objStreamRead.ReadToEnd()
' Check if available, then close response
If Not objResponse Is Nothing Then
objResponse.Close()
End If
Catch
' Error occured grabbing data, simply return nothing
Return ""
End Try
End Function
now when i remove the switch statement and just write the objResponse as
objResponse = objRequest.GetResponse
except i get an exception of error 403 or 503, i don't know how to handle this.

Answer 1

Your error line:
Select Case CType(objResponse, Net.HttpWebResponse).StatusCode
is called without ever assigning anything to objResponse.
You need to change it to:
objResponse = objRequest.GetResponse
Select Case CType(objResponse, Net.HttpWebResponse).StatusCode`
In regards to getting HTTP error codes for the page you are trying to ftech, here are the meanings of them and their causes:
http://en.wikipedia.org/wiki/List_of_HTTP_status_codes

Answer 2

First off, tcarvin is correct, your question's code is missing this line:
objResponse = objRequest.GetResponse
Secondly, you can do this to resolve your other issue:
If Not objResponse Is Nothing Then
'Select Case Code
Else
'Handle failure.
End If