No, you haven't done anything wrong, it's just that pitivi 0.13.6 (or 0.14? I'd prefer it to be named that way...) has not been released yet.

If you'd like to try out effects and the new rendering UI (among other things), maybe you want to play with the git version (see the website on how to do that). It can be used separately from your "normal" pitivi install and the gstreamer PPA should provide you with recent-enough gstreamer packages.