Failed to load result from task

In the latest version of my email archiving app I've changed most Chilkat related code to the async methods. I've now got 2 error reports from testers that this sometimes doesn't work. The code does 2 passes: first a header is downloaded. The message ID is checked if it's already in the database. If it's not then the full mail is downloaded with the following code:

dim messageID as Integer = CkoMessageSet.getID(counter - 1)
CkoMailTask = CkoImap.FetchSingleAsMimeAsync(messageID, True)
call CkoMailTask.run
While CkoMailTask.Finished <> true
  CkoMailTask.SleepMs(50)
wend

if not CkoMailTask.TaskSuccess then
  Globals.theErrorLog.LogItem(CurrentMethodName + " " + MailboxPath +  " task didn't finish")
  Return ""
end if

dim theBody as String = CkoMailTask.GetResultString
if theBody = "" then
  globals.theErrorLog.LogItem(CurrentMethodName + " " + MailboxPath +  " wasn't able to load result from task")
  globals.theErrorLog.LogItem(CurrentMethodName + " " + MailboxPath +  setLastErrorForTask(CkoMailTask))
end if

And now the relevant part of the error log when the mail body is empty:

2017-08-25, 9:52:10 AM ImapIterator.GetNumberOfObjects INBOX 25517
2017-08-25, 12:57:58 PM ImapController.getMail INBOX wasn't able to load result from task
2017-08-25, 12:57:58 PM ImapController.getMail INBOXChilkatLog:
  FetchSingleAsMime:
    DllDate: May 25 2017
    ChilkatVersion: 9.5.0.68
    UnlockPrefix: xxx
    Architecture: Little Endian; 32-bit
    Language: MAC OS X C/C++
    VerboseLogging: 0
    msgId: 236230
    bUid: 1
    fetchSingleComplete:
      autoDownloadAttachments: 1
    --fetchSingleComplete
    Success.
  --FetchSingleAsMime
--ChilkatLog

Xojo 2017r1, macOS 10.12.6.

Is this a problem or can I ignore the mail?

Mit freundlichen Grüßen/Regards

Beatrix Willius

http://www.mothsoftware.com Mail Archiver X: The email archiving solution for professionals