jQuery fileupload not working in IE 8 and 9

Question

This code works in FF and chrome. In IE 8 or 9 I get a 500 error saying a not

Answer 1

            $("#txt1").fileupload({
            replaceFileInput: false,
            dataType: "json",        
            datatype:"json",
            url: "<%=Page.ResolveUrl("~/WebService/AddAttachment.ashx")%>",
            done: function (e, data) {
                $.each(data.result, function (index, value) {
             //You get the response data in here from your web service
                })
                $("#txt1").val("");
            }`enter code here`
        }); 

This is tested and working fine in both IE8 and IE9 + above. Please make sure to use the correct dataType:"json" (or datatype:"json") and also make sure your response of web service method is correct. Thanks