[Solved] Can't play on hard

[Gus]

I played the entire game on normal, finished it yesterday. I did some missions on easy to get the robot achievements, and now I want to play it in hard but all the levels are locked. I already tried beating the boss on normal again but that didn't worked. Do I need to finish the game on easy too to unlock hard?
Here is a screenshot of the locked levels
http://puu.sh/93ul7.jpg

[Gus]

I redid the campaign on normal and now hard is unlocked.