OK, I'll apply my limited C-Script skills and see how we go.

1> Try changing the my.enable_impact = on; line to be my.ENABLE_IMPACT = on;
just in case capitals for ENABLE_IMPACT is important.(I dont think it is though)

2> Try adding (before my.event gets set) my.push = 100;
(This entities push value must be higher than whatever it gets hit by)

3> Show us the "Level_A" function, in case its something wrong in there...

Otherwise everything looks OK to my limited skills.