Slimes and Magma Cubes do not get removed using /entitydata @e[type=!Player] {Health:0,DeathTime:19}

The command: /entitydata @e[type=!Player] {Health:0,DeathTime:19}, should remove an entity so it get's killed without it dropping any items. My tests have concluded that the command works on every friendly creature and mob except for the slime and magma cube, pls fix it 😉