在部署c#mvc之后将文件上载到服务器时出错

我正在c#mvc中创建一个应用程序，用户可以在其中上传mp3文件，下面是我的上传控制器：

    [HttpPost]
    public ActionResult Index(HttpPostedFileBase file)
    {
        string x = Request["ss"];
        song std = new song();
        if (file != null && file.ContentLength > 0)
            try
            {
               // string path = Path.Combine(Server.MapPath("~/Songs"), Path.GetFileName(file.FileName)); 
               string path = "~/Songs/" + Path.GetFileName(file.FileName);
                var allowedExtensions = new[] { ".mp3",".MP3" };
                var extension = Path.GetExtension(file.FileName);
                if (!allowedExtensions.Contains(extension))
                {
                    ViewBag.Message = "Only .mp3 extension files are allowed!!";
                }
                else
                {
                    file.SaveAs(Server.MapPath(@"~'Songs'" + file.FileName));
                    //file.SaveAs(path);
                    string[] arr = { };
                    arr = (file.FileName).Split('.');
                    std.name = arr[0];
                    if (x == null || x == "")
                    {
                        std.artist = "Not Mentioned";
                    }
                    else {
                        std.artist = x;
                    }
                    std.likes = "0";
                    std.dislikes = "0";
                    repo4.save4(std);       //call the function..
                    ViewBag.Message = "Song uploaded successfully!! ";
                }
            }
            catch (Exception ex)
            {
                ViewBag.Message = "ERROR:" + ex.Message.ToString();
            }
        else
        {
            ViewBag.Message = "You have not specified a file.";
        }
        return View();
    }

以下是我对index.cshtml:的看法

@using (Html.BeginForm("index", "Upload", FormMethod.Post, new { enctype ="multipart/form-data" }))
            {
                <label class="l" for="file">Upload Song:</label>
                <input class="l" type="file" name="file" id="file" />
                <div class="form-inline form-group">
                    <label class="l">Artist' Name : &nbsp;</label>
                    <input type="text" class="form-control" name="ss" maxlength="30" placeholder="Leave it blank if u want.." />
                </div>
                <input type="submit" class="btn btn-warning" value="Upload" />
                <div class="text-danger">@ViewBag.Message</div><br /><div class="text-success">Search uploaded song <a href="/Reg/reg">HERE</a></div>
            }

现在，我将mp3文件保存到名为Songs的文件夹中。。当我在VS上构建项目时，这段代码似乎运行得很好。但在AppHarbor上部署后，当我尝试上传mp3文件时，我不断收到以下错误：

错误：访问路径'D:''Users''apphb180c99d1921484''app_PublishedWebsites''WebMatrixWebsite''Songs''Wake"Me Up.mp3"被拒绝。

请提供任何帮助，我将不胜感激，因为我无法理解…谢谢！！