call secure web service (thru cer) from a web service

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I have a vb.net web service. I am trying to call another webservice that is
secured through certificate. I have received the certificate file and I am
trying to call the service using the file. I am having some challenges such
as:

1. I can not add a web reference to the secure service. Error: The request
failed with HTTP status 400: Bad Request.
2. to overcome this, I asked for a proxy class. I received the dll and I
added it as a reference in bin. I then have the following code:
=============== =============== =========
Dim cert1Path As String = "certificate1.c er"
Dim cert2Path As String = "certificate2.c er"
Dim proxy As New SecuredWebServi ce()
Proxy.Url = "https://url.asmx"
proxy.ClientCer tificates.Add(X 509Certificate. CreateFromCertF ile(cert1Path))
proxy.ClientCer tificates.Add(X 509Certificate. CreateFromCertF ile(cert2Path))

result=proxy.me thod()
=============== =============== =============== =

I get an error when I do that:
"Request for the permission of type 'System.Net.Web Permission, System,
Version=2.0.0.0 , Culture=neutral , PublicKeyToken= XXXXXXXXXXXXX' failed"

3. Can some one do me a big favor and tell me how I can refer to a file
under App_Data or App_Code other than using "~/App_Code/Filname". I get an
error when I move the code to the server and run it using the url versus
Visual Studio start button. It complains that "File not found" or

Parser Error
Description: An error occurred during the parsing of a resource required to
service this request. Please review the following specific parse error
details and modify your source file appropriately.

Parser Error Message: Could not create type 'XXXXX'.

Source Error:
Line 1: <%@ WebService Language="vb" CodeBehind="~/APP_Code/XXXXXX.vb"
Class="XXXXX" %>