title: object reference not set to an instance of an object xdocument
body: <p>Hi I get an error on the line commented in the below code <code>object reference not set to an instance of an object</code> is there a way to fix it? </p>
  
  <pre><code>    private void button20_Click(object sender, EventArgs e)
      {
          string blabla1 = string.Format("http://localhost:8000/Service/AuthenticateUser/{0}/{1}", textBox30.Text, textBox31.Text);
          XDocument xDoc = XDocument.Load(blabla1);
          xDoc.Element("StudentID").Value.ToList(); // object reference not set to an instance of an object?
  
  
          dataGridView12.DataSource = xDoc;
      }
  </code></pre>