XMLHttpRequest, Object doesn't support this property or method, IE8 Error

I'm currently debugging IE issues on an application.

I'm getting an 'Object doesn't support this property or method' when I try to .addEventListener to my XMLHttpRequest object.

Code:

var xhr = new XMLHttpRequest();

xhr.addEventListener("load", function() {
    me.fireEvent('saveComplete', this);
}, false);

It seems to me that in IE8 the addEventListener method isn't being recognized as a method for my xhr object.

Any ideas on how to fix or debug this issue further?

Thanks!