När jag använder nedan kod på min ascx sidan får jag ett felmeddelande i webläsaren. Så fort jag lägger annan kod i subben så funkar det. Vad är galet?

<code>
Protected Sub nalla()

Dim Client As New WebClient 'WebClient =
Client.DownloadFile("http://www.test.se/test.jpg", "minbild.jpg")

End Sub
</code>

<code>
Server Error in '/wwwroot' Application.
--------------------------------------------------------------------------------

Invalid postback or callback argument. Event validation is enabled using <pages enableEventValidation="true"/> in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.
</code>