Cannot set label's content to zero : <p>I've got the following coding where I am trying to step through a couple of <code>if</code> statements, but I've got a problem with setting my label's content to <code>0</code>;</p>

<pre><code>private void UnderRunBumper()
{
    lblGVMAmount.Content = 0; //Issue here
    if (Convert.ToInt32(txtExternalLength.Text) &gt;= 6000)
        lblUnderRunBumper.Content = "Under-Run Bumper";

    else if (Convert.ToInt32(lblGVMAmount.Content.ToString()) &gt;= 8000)
        lblUnderRunBumper.Content = "Under-Run Bumper";

    else if (cmbBodyType.SelectedIndex == 6 || cmbBodyType.SelectedIndex == 7 || cmbBodyType.SelectedIndex == 8 || cmbBodyType.SelectedIndex == 9 || cmbBodyType.SelectedIndex == 10)
        lblUnderRunBumper.Content = "Under-Run Bumper";
    else lblUnderRunBumper.Content = "";
}
</code></pre>

<p>I get the error:</p>

<blockquote>
  <p>Object reference not set to an instance of an object.</p>
</blockquote>

<p>I don't understand. Why can't I set my label's value to 0?</p>
