@Anak
I do not have a Kobo myself, but maybe this could help.
Have you set in config_local.php:
Code:
/*
* Rename .epub to .kepub.epub if downloaded from a Kobo eReader
* The ebook will then be recognized a Kepub so with chaptered paging, statistics, ...
* You have to enable URL rewriting if you want to enable kepup.epub download
* 1 : Yes (enable)
* 0 : No
*/
$config['cops_provide_kepub'] = "0";
to "
1"? (and then enabled URL rewriting?)