I have the following code that populates a select element with values from an ajax call, via a Page Method. In FF, the code works perfectly, in IE8 I get the error: 'ResourceList[...].id' is null or not an object. What can I look at here?

    function readShift(jsonString) {
        var shiftInfo = Sys.Serialization.JavaScriptSerializer.deserialize(jsonString);
        var listItems = "";

        listItems += "<option value='0'>[Unassigned]</option>";
        for (var i = 0; i < shiftInfo.ResourceList.length; i++) {
            listItems += "<option value='" + shiftInfo.ResourceList[i].id + "'>" + shiftInfo.ResourceList[i].name + "</option>";
        }
        $("#" + resourceListId).html(listItems);
     };