commands problem

I'm creating a mini game (spleef) but these commands don't work in minecraft pe.

1) /testfor @a[x=507,y=0,z=17,dx=30,dy=8,dz=30]
Detects all players who are in the zone.

2) /kill @a[x=507,y=0,z=17,dx=30,dy=2,dz=30]
Kills all players who fall into the void.