Solved.
Hello everyone, good night. First of all, I do not speak English, forgive my grammatical errors, but I'm using a translator. (a.k.a. Google). Well, I'm new here and I have a very basic problem. Better show than talk:
As the guides for beginners recommend, I create a "Player Box" to perform the animations of the character - if this could be the error.
I certainly did something wrong and I can not identify. I've even checked the collisions of the box, the platform and each frame of the animations: that's fine. If it is a useful information, each animation has only two frames - except "Jumping" that has only one. And I'm still using the free version, I plan to buy a license as soon as possible. That's it, I'm sorry for taking your time.