Can anyone advise why I get an error when attempting to read back the file saved by the code below?

Exception is at line 47 below:

exception: com.filepool.fplibrary.FPLibraryException: tag should have a blob

  @Override
  public String storeDocument(Document document) throws DocumentStoreException
  {
  
    String clipId = null;


    try
    {
  
      InputStream inputStream = document.getFile().getInputStream();
      FPClip clip = createClip();
      FPTag topTag = clip.getTopTag();
      // createDocumentAttributesTag(topTag, document);
      FPTag tag = new FPTag(topTag, "StoreContentObject");
      tag.BlobWrite(inputStream);


      clipId = clip.Write();


      inputStream.close();
      tag.Close();
      topTag.Close();
      clip.Close();
    }
    catch (Exception ex)
    {
  
      throw new DocumentStoreException("Error Saving Document", ex);
    }


    return clipId;
  }

  @Override
  public byte[] retrieveDocument(String id) throws DocumentStoreException
  {
  
    byte[] data = null;


    try (ByteArrayOutputStream baos = new ByteArrayOutputStream())
    {
  
      FPClip clip = new FPClip(pool, id, FPLibraryConstants.FP_OPEN_ASTREE);
      FPTag topTag = clip.getTopTag();
      // FPTag tag = topTag.getFirstChild();


      topTag.BlobRead(baos);
      //tag.BlobRead(baos);
      data = baos.toByteArray();


      if (LOGGER.isDebugEnabled())
      {
  
        writeDebugData(topTag);
      }


      // tag.Close();
      topTag.Close();
      clip.Close();
    }
    catch (Exception ex)
    {
  
      throw new DocumentStoreException("Error Retrieving Document", ex);
    }


    return data;
  }

  protected FPClip createClip() throws FPLibraryException
  {
  
    FPClip clip = new FPClip(pool, Long.toString(System.currentTimeMillis()));


    clip.setDescriptionAttribute("app-vendor", "xxx");
    clip.setDescriptionAttribute("app-name", "xxx");
    clip.setDescriptionAttribute("app-version", "xxx");


    clip.setRetentionPeriod(100);


    return clip;
  }