I need help, Dynamics-Set mass

Hi, I have a problem with the Edit Object actuator.
I’m using the option Dynamics-Set mass with keyboard sensors for variable weighing an object, but I can’t get it to work well.
In physics I have established the mass of the object in 1, pressing spacebar, the object’s mass would be 5, and pressing LeftCtrl, would be 3, the first times it works, but it is impossible to start a new cycle, does anyone know why ?

Thanks

keyboard_and_dinamics (set mass)3.blend (543 KB)