Http状态404：文件上载时未找到错误

Question

我上传的文件是55MB。允许的最大文件大小为49MB。我的代码是：

private void AddFilePartToVault(FileInfo fileInfo, long folderId, 
                                WebServiceManager manager)
{
    Guid guid = Guid.Empty;

    using(FileStream stream = new FileStream(fileInfo.FullName,
                               FileMode.Open,FileAccess.Read))
    {

        ByteArray array = new ByteArray();
        array.Bytes= new byte[MaxFileSize];

        long unreadBytes;
        while ((unreadBytes = stream.Length-stream.Position)>0)
        {

           if (unreadBytes < MaxFileSize)
           array.Bytes=new byte[unreadBytes];

            stream.Read(array.Bytes,0,array.Bytes.Length);
            try
            {
                guid = manager.DocumentService.UploadFilePart(guid, array);
            }
            catch (System.Net.WebException we)
            {
                MessageBox.Show(we.Message);
            }
       } 

使用此功能，上传第二部分6MB，不上传第一部分49MB。引发异常Http状态404未找到。