Well, I have solved it. the main problem is that the collision with physic do not work well, I dont know why. When an object collision with other and both have physic then you are catching the current velocity and if you trying compare to collision to both objets in that instant the collison sometimes not occurs in the moment of the velocity expected. whatever!
A solution I found is use a sprite auxiliar which detecte the collision but HAVE NOT the physics behavior, so this sprite auxiliar is largest in size that the object with physic.physic
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