ajaxFileUpload上传excel到node端，为什么undefined，传不上去

前端：
function fileUpload(url, data, file, callback) {

    $.ajaxFileUpload(
            {
                url: url,            //需要链接到服务器地址
                secureuri: false,
                data: data,
                file: file,                        //要上传的文件
                dataType: 'json',                                     //服务器返回的格式，可以是json,xml
                success: function (back,status)            //相当于java中try语句块的用法
                {
                    callback(back);
                    console.log("444--"+back)
                },
                error: function (back, status, e)            //相当于java中catch语句块的用法
                {
                    callback(back);
                    console.log("111---"+back+"222---"+status+"333---"+e)
                }
            }
    );
}


     fileUpload('/importTeacher', "", xlsFile, function (back) {
                    console.log(xlsFile);
                    console.log("back--"+back);
                    queryHintCallback("query_hint");
                    $("#importTeacher").removeClass("pltj_disable").addClass("pltj_input");
                    var bd = JSON.parse(JSON.stringify(back)).responseText;
                    if (bd.indexOf("success") != -1) {
                        alertMsg("导入成功!");
                        setTimeout("history.go(-1)", 1300);
                    }else{
                        alertMsg(bd);
                    }
                });

node端：
exports.importTeacher = function(req,res)
{

    res.writeHead(200, {"content-type": "text/plain"});
    var user = req.session.user;
    var qd = util.getData(req);
    var files = req.files;
            这个files为undefined？？？？？？？？？？？？？
    var data = {
        kindergartenCode: user.data.kindergartenCode
    };
    for (var name in files) {
        var file = files[name];
        var image = base64_encode(file.path);
        data.excels = image;
        generalService.teacherService_post("/importTeachers",data,user.token,function (back) {

            unlinkFile(file.path);
            try{
                var data = JSON.parse(back);
                res.end(data.msg);
            }
            catch(e)
            {

                res.end("error");
            }
        });
    }
    console.log("fail666666666666666666666666666666")
}