在Zipping中覆盖文件

我尝试在C#中压缩一些.pdf文件。我的代码运行得很好，但当其中一个pdf的大小很大时，它会覆盖其余的pdf。我不确定发生了什么事。我试图增加缓冲区或zip文件的大小，但仍然存在同样的问题。你有什么建议吗？

这是我的代码：

    public void ProcessZipRequest(string strQueueID, string strBatchID, string strFtpPath)
    {
        int intReportCnt = 0;
        string strZipFileName = "Order-" + strBatchID + "-" + strQueueID + "-" + DateTime.Now.ToString("MM-dd-yyyy-HH-mm") + ".zip";
        strZipFileName = SafeFileName(strZipFileName);
        //MemoryStream ms = new MemoryStream();
        FileStream ms = new FileStream(@"c:'surf'nikoo.zip", FileMode.Create);
        ZipOutputStream oZipStream = new ZipOutputStream(ms); // create zip stream
        oZipStream.SetLevel(9); // maximum compression
        intReportCnt += 1;
        string strRptFilename=string.Empty;
        MemoryStream outputStream = new MemoryStream();
        if (strQueueID != null)
        {

            String[] filenames = Directory.GetFiles(@"C:'uploaded");
            // setting Report name to path given for Report name
            foreach (String filename in filenames)
            {
                strRptFilename = filename.Substring(filename.LastIndexOf("''") + 1);

                FileStream fs = File.OpenRead(@"C:'uploaded'" + strRptFilename);
                int bufferSize = 2048;
                int readCount;
                byte[] buffer = new byte[bufferSize];
                readCount = fs.Read(buffer, 0, bufferSize);
                while (readCount>0)
                {
                    outputStream.Write(buffer, 0, readCount);
                    readCount = fs.Read(buffer, 0, bufferSize);
                }
                fs.Close();
                outputStream.Position = 0;

                ZipFile(ref outputStream, strRptFilename, ref oZipStream);
            }
        }
        outputStream.Close();
        oZipStream.Finish();
        oZipStream.Flush();
        oZipStream.IsStreamOwner = false;  //  False stops the Close also Closing the underlying stream.
        oZipStream.Close();                // Must finish the ZipOutputStream before using outputMemStream.
        ms.Close();
    }

这就是Zipfile方法：

   public void ZipFile(ref MemoryStream msFile, string strFilename, ref ZipOutputStream oZipStream)
    {
        ZipEntry oZipEntry = new ZipEntry(strFilename);
        oZipEntry.DateTime = DateTime.Now;
        oZipEntry.Size = msFile.Length;
        oZipStream.PutNextEntry(oZipEntry);
        StreamUtils.Copy(msFile, oZipStream, new byte[4096]);

        oZipStream.CloseEntry();
    }

foreach (String filename in filenames)
            {
                strRptFilename = filename.Substring(filename.LastIndexOf("''") + 1);
                outputStream = new MemoryStream();
                FileStream fs = File.OpenRead(@"C:'uploaded'" + strRptFilename);
                int bufferSize = 2048;
                int readCount;
                byte[] buffer = new byte[bufferSize];
                readCount = fs.Read(buffer, 0, bufferSize);
                while (readCount>0)
                {
                    outputStream.Write(buffer, 0, readCount);
                    readCount = fs.Read(buffer, 0, bufferSize);
                }
                fs.Close();
                outputStream.Position = 0;

                ZipFile(ref outputStream, strRptFilename, ref oZipStream);
                fs.Close();
                outputStream.Close();
            }