急：一个ajax上传的问题

Question

public string UpLoadFile(string fileNamePath, string toFilePath)    {        try        {            //获取要保存的文件信息            FileInfo file = new FileInfo(fileNamePath);            //获得文件扩展名            string fileNameExt = file.Extension;            if (file.Length > 41943040)            {                return "0|errorfile|上传文件不能超过40M";            }            //验证合法的文件            if (CheckFileExt(fileNameExt))            {                //生成将要保存的随机文件名                string fileName = GetFileName() + fileNameExt;                //检查保存的路径 是否有/结尾                if (toFilePath.EndsWith("/") == false) toFilePath = toFilePath + "/";                 //按日期归类保存                string datePath = DateTime.Now.ToString("yyyyMM") + "/" + DateTime.Now.ToString("dd") + "/";                if (true)                {                    toFilePath += datePath;                }                 //获得要保存的文件路径                string serverFileName = toFilePath + fileName;                //物理完整路径                                    string toFileFullPath = HttpContext.Current.Server.MapPath(toFilePath);                 //检查是否有该路径  没有就创建                if (!Directory.Exists(toFileFullPath))                {                    Directory.CreateDirectory(toFileFullPath);                }                 //将要保存的完整文件名                                string toFile = toFileFullPath + fileName;                 ///创建WebClient实例                       WebClient myWebClient = new WebClient();                //设定windows网络安全认证   方法1                myWebClient.Credentials = CredentialCache.DefaultCredentials;                //设定windows网络安全认证   方法2                //NetworkCredential cred = new NetworkCredential("SINOPANEL/xiangnan-xiao", "xiaoxiangnan");                //CredentialCache cache = new CredentialCache();                //cache.Add(new Uri("UploadPath"), "Basic", cred);                //myWebClient.Credentials = cache;                 //要上传的文件                       FileStream fs = new FileStream(fileNamePath, FileMode.Open, FileAccess.Read);                //FileStream fs = OpenFile();                       BinaryReader r = new BinaryReader(fs);                //使用UploadFile方法可以用下面的格式                       //myWebClient.UploadFile(toFile, "PUT",fileNamePath);                       byte[] postArray = r.ReadBytes((int)fs.Length);                Stream postStream = myWebClient.OpenWrite(toFile, "PUT");                if (postStream.CanWrite)                {                    postStream.Write(postArray, 0, postArray.Length);                }                else                {                    return "0|" + serverFileName + "|" + "文件目前不可写";                }                postStream.Close();                 return "1|" + serverFileName + "|" + "文件上传成功";            }            else            {                return "0|errorfile|" + "文件格式非法";            }        }        catch (Exception e)        {            return "0|errorfile|" + "文件上传失败,错误原因：" + e.Message;        }    } 这是我用的ajax上传的  在本地可以   但是传到服务器上就不能上传了  提示未能找到文件，烦请各位大虾解救