The server method 'UnlockRecord' failed with the following error: '

 I've spent the past 20 minutes scouring Google on this one, and I've got nothing. I have a JavaScript snippet in my page:
 
<script type="text/javascript">
window.onbeforeunload=UnloadMe;

function UnloadMe()
{
if(document.getElementById('ctl00_ContentPlaceHolder1_lblLocked').innerHTML != '')
ICE.Activations_Services.UnlockRecord(document.getElementById('ctl00_ContentPlaceHolder1_txtInstallCardNumber').value, document.getElementById('ctl00_ContentPlaceHolder1_lblLocked').innerHTML.substring(18, document.getElementById('ctl00_ContentPlaceHolder1_lblLocked').innerHTML.length));
}
  
When I put an anchor on the page that calls that method, it runs flawlessly. However, when I reload the page to t ...