Note Attachment - DownloadAttachment() receive Empty ResponseJSON

Note Attachment - DownloadAttachment() receive Empty ResponseJSON

Hello,
I'm trying to get an attachment from Notes Record using c# sdk.
The problem is that I get an empty response even if attachment exists.
Please see the code below:

1. First I get the "Note" instance.
  1. ZCRMRecord recordIns = ZCRMRecord.GetInstance("Notes", {_note_ID_});
2. get The attachment - try to download attachment
  1. FileAPIResponse response = recordIns.DownloadAttachment({_attachment_ID_});
3. received:
  1.     {STATUS_CODE=OK,RESPONSE_JSON=,RESPONSE_HEADERS=X-RATELIMIT-LIMIT=0;X-RATELIMIT-       REMAINING=0;X-RATELIMIT-RESET=0;}
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Also have tried another way:

1. Get account
  1. ZCRMModule accountsInstance = ZCRMModule.GetInstance("Accounts");
2. Search account by criteria
  1. ZCRMRecord account = accountsInstance.SearchByCriteria(.........)
3. Get all Notes
  1. List<ZCRMNote> notes = account .GetNotes();
4. Loop through notes list
5. Get Note Attachments
6. Try to Download attachment
  1.      var attachment = note.Attachments[0]
  2.      var tst = item.DownloadAttachment(attachment.Id);
  3.      //Receive empty response

  5. {STATUS_CODE=OK,RESPONSE_JSON=,RESPONSE_HEADERS=X-RATELIMIT-LIMIT=0;X-RATELIMIT-REMAINING=0;X-RATELIMIT-RESET=0;}