Custom Mob Spawners Broken

On 15w34b, I made Custom Mob Spawners. When I clicked the command block to make it, the entity inside was a PIG. even thought I clearly put id Skeleton.I made simpler ones but no luck. all are pig spawners

My Command: /setblock ~ ~0 ~ minecraft:mob_spawner 0 replace

{EntityId:Skeleton}

It was a Pig Spawner Again. Anyway, Ive tried lots of other ways but it simply doesn't work anymore