I have a Kobo Mini, which is 2 years old, I'm trying to transfer an e-book from a website on my Laptop, onto the Kobo but it isn't allowing me. It's saying "E_IO_CANNOT_OPEN - Failed to write destination file". Any ideas whats causing this? I have auth

[prestatynl1b]

I have a Kobo Mini, which is 2 years old, I'm trying to transfer an e-book from a website on my Laptop, onto the Kobo but it isn't allowing me.  It's saying "E_IO_CANNOT_OPEN - Failed to write destination file".  Any ideas whats causing this?  I have authorised my device and done what I thought was the necessary.  It states on the Kobo website that the Mini does allow DRM but it's not working, maybe the Mini that's on the website is more advanced than the one I have, because it's a couple years old now.  Any Ideas?  Help greatefully appreciated :)!