Memorystream.Read()总是返回0字节Read，字节[]为空

我当前有一个长度约为30000（Named memStream here）的内存流我希望使用以下代码在chunks中读取此内存流（我在网上找到并进行了一些修改）：

        byte[] chunk = new byte[4096];
        bool hasNext = true;
        while(hasNext)
        {
            int index = 0;
            while (index < chunk.Length)
            {
                int bytesRead = memStream.Read(chunk, index, chunk.Length - index);
                if (bytesRead == 0)
                {
                    break;
                }
                index += bytesRead;
                //Do something with this chunk
            }
            if (index != 0) // Our previous chunk may have been the last one
            {
                //Do something with the last chunk
            }
            if (index != chunk.Length) // We didn't read a full chunk: we're done
            {
                hasNext = false;
            }
        }

然而，下面的read()方法似乎不起的作用

  int bytesRead = memStream.Read(chunk, index, chunk.Length - index);
  WHERE
    chunk: new byte[4096]
    index: 0
    memstream: capacitiy & length : 34272
    memstream: position 0 (according to VS watch)
 Always returns
    0 bytesRead
    Chunk with all values containing '0'

知道为什么吗？这可能是权限许可吗？

谢谢你抽出时间。

memStream.Seek(0, SeekOrigin.Begin);