Exception handling in AJAX

[jananivenkatesan]

I am using Seam to develop portlets on Jboss Portal Platform. I had a question about handling AJAX errors in Seam. I used the following code to handle exceptions in AJAX calls:

xhtml :

<script type="text/javascript">  
        A4J.AJAX.onError = function(req,status,message){  
                alert("error occured " + message);
        };
</script>

<h:form id="loadPanelForm" > 
  <a4j:commandLink value="Edit" action="#{myLinksAction.loadMyLinksForEdit}" reRender="myLinksEditForm" oncomplete="if (#{facesContext.maximumSeverity==null}) #{rich:component('myLinksEditPanel')}.show();"/>
</h:form>

Function:

public void loadMyLinksForEdit() {
     throw new IllegalStateException("Exception while trying to load links");
}

However, I do not see the alert message when an exception occurs.

Can you please help me with this?