I got 99,9% of the game.
I collected all lums (all 999), broke all cages (all 80), I won mini race with Globox's baby against that Razobeard servant, I beat Razorbeard, so I've pretty much everything, haven't I?

So why when I want to load my profile it shows only 99,9% instead of 100%.

What else I have to do? It is some kind of a bug or I missed something?

There's a secret 1000th Lum you need to collect :) If you Google for it you'll find some videos on where it is.