IE6 에서 AJAX 사용시 onexception 발생할때는 어떻게 해야되나요..

var CTest = Class.create();
CTest.prototype = { 
    initialize :function(){},
    Test : function(){
        var url = 'http://test.com/test.html';
        var testAjax = new Ajax.Request(
                url,
                {
                    method:'get',
                    onSuccess : this.TestResponse,
                    onException : function(req,exception){alert(req + '//' + exception);}
                })  
    },
    TestResponse : function(originalRequest){
        alert(originalRequest.responseText);
    }
}
 
var objTest = new CTest();
window.onload = function()
{
    objTest.Test();
}

Compatibility
The latest version of Prototype is compatible with the following browsers:
 
Browser Version(s) 
Mozilla Firefox ≥ 1.5 
Microsoft Internet Explorer ≥ 6.0 
Apple Safari ≥ 2.0 
Opera ≥ 9.25