It is really weird how book sales happen. I published an ebook back in June 2014 which sold only 3 copies in 2014, nothing at all from January to May 2015 and then it started selling on Scribd and Google from June 2015 onwards. It hardly ever sells on Kindle.
If only one knew why it sells in one bookstore and not another.
I guess that this only proves that you should never give up hope!