Hero XP Gain questions

So i've got this problem, unreliable of gameplay constants, that hero's in map all gain the same XP, no matter who gets the kill. Now what i'm asking is the solution for this. Only the one that kills should get the Exp.

Should i go trigger this or do it with something else?

All comments welcome |||Are Your Units near the Hero you have training or rather far from him?? If they are close to him they get a percentage of the exps he gains.