I can’t preview post’s change once they are published

The preview function works fine when posts are just draft. The url looks like this :
http://exemple.domain.com/blog/?p=12&preview=true

Then when I pubish my posts, let’s say I want to change something and preview it, the url looks like this : http://exemple.domain.com/blog/my-article-title/?preview=true&preview_id=12&preview_nonce=514e88946a&post_format=standard

The problem is it does reflect any changes …

I use WordPress 3.9.2 running Twenty Fourteen theme without any plugins

EDIT

I’ve turn the permalink to default and it resolve the problem. But I need it to work using the pretty url …
Thanks for your help