Be sure that you're editing the correct transitions.ini

In my case, I have a theme, so it does *not* use

/usr/share/hildon-desktop/transitions.ini

it uses instead

/usr/share/theme/transitions.ini

What I did is to make a link between both files.

Inside the theme folder, you can first backup the current transitions.ini and then

ln -s /usr/share/hildon-desktop/transitions.ini transitions.ini