Fine uploader Async任务在Chrome中工作，但在IE11中不工作

我使用Fineuploader Promise在提交回调中运行md5检查，以防止已经存在的文件再次上传，它在chrome中工作，但在IE11中不工作。不是IE错误还是我做错了?我怎样才能修好它?非常感谢。脚本如下:

 $("#uploader").fineUploader({
    request: {
        endpoint: 'home/upload'
    },
    multiple: true,
    autoUpload: false,
    debug: true,
    chuncking: {
        enabled:true
    },
    editFilename: {                                            
        enable: true
    },
    validation: {
        sizeLimit: 1073741824
    }
}).on({                                                      
    "complete": function (event, id, fileName, responseJSON) { 
        if (responseJSON.success) {
            alert("upload success");
        }
    },
    "validate": function (event,data) {
    },
    "submit": function (event,id, fileName) {             
        var promise = new qq.Promise();
        var file = $(this).fineUploader('getFile', id);
        var freader = new FileReader();
        validateMD5(file, freader,promise);
        return promise;
    },
    "error": function (event, id, fileName, reason) {
        alert(reason);
    }
});

$("#uploadButton").click(function () {
    $('#uploader').fineUploader('uploadStoredFiles');
});
function validateMD5(file, reader,promise) {
    var blobSlice = File.prototype.mozSlice || File.prototype.webkitSlice || File.prototype.slice;
    var spark = new SparkMD5();
    var chunkSize = 2097152;
    var chunks = Math.ceil(file.size / chunkSize);
    var currentChunk = 0;
    var start1 = 0;
    var end1 = chunkSize >= file.size ? file.size : chunkSize;
    reader.readAsBinaryString(blobSlice.call(file, start1, end1));
    reader.onload = function (e) {
        spark.appendBinary(e.target.result);
        currentChunk++;
        if (currentChunk < chunks) {
            var start = currentChunk * chunkSize;
            var end = start + chunkSize >= file.size ? file.size : start + chunkSize;
            reader.readAsBinaryString(blobSlice.call(file, start, end));
        } else {
            var md5 = spark.end();
            var r = checkMd5Onserver(md5);
            if (r == true) {
                promise.success();
            } else {
                promise.failure();
            }
        }
    };
}
function checkMd5Onserver(md5) {
    return false;//just for test
}