title: Page.ClientScript.RegisterStartupScript does not work
body: <p>I am currently in the process of migrating an old system to another server and when I tested the application, my popup windows displays a blank page. Please see below the code which is used to display my popup message:</p>
  
  <pre><code>Private Sub ShowPopUp(ByVal myID As String, ByVal request As String, ByVal windowType As String, ByVal code As String)
      Dim popupScript As String = "&lt;script language='javascript'&gt;" &amp; _
                                      "window.open('NewWindow.aspx?windowType=" &amp; windowType &amp; "&amp;id=" &amp; myID &amp; _
                                      "&amp;code=" &amp; code &amp; "&amp;popup=" &amp; request &amp; "&amp;kind=3', 'CustomPopUp', " &amp; _
                                      "'width=700, height=400, menubar=no, resizable=yes')" &amp; _
                                  "&lt;/script&gt;"
  
      Page.RegisterStartupScript("PopupScript", popupScript)
  End Sub
  </code></pre>
  
  <p>Now this used to work perfectly on the old site and on local. However, once transferred to the new server, I keep getting the warning that <code>Page.RegisterStartupScript is obsolete</code> and that it should be changed to <code>Page.ClientScript.RegisterStartupScript</code>. So I did the changes, please see below:</p>
  
  <pre><code>Page.ClientScript.RegisterStartupScript(Me.GetType(), "PopupScript", popupScript, True)
  </code></pre>
  
  <p>However, these doesn't work. It shows a blank page on my popup contrary to the result of running the application on my local with the 'old' way which shows my desired output. </p>