Problem with transfer_log

[Juan Simón]

When lftp downloads finished, I see *transfer_log* file to delete those
downloaded files in my server. After I empty this file (*with an text editor
*) and I save it.
The problem is that if I don't restart lftp, after I empty the *transfer_log
* file, lftp doesn't saved the next downloads in this file.
Regards.