Summoning with equipment tag doesn't work

Using /summon with an equipment tag completely ignores the equipment tag.

1) Summon a zombie using this command :
/summon Zombie ~ ~ ~ {Equipment:[

{id:stone_sword,Count:1b}

,{},{},{},{}]}

2) Witness the zombie spawning without the sword

I tried putting the minecraft: before the item names and tweaking around the Count, but every try has been a failure, so I think there actually is something wrong. Either that or the system has changed without me knowing.