[MC-38106] DropChances don't seem to be working, even with correct format.

I have one code that works:

/summon Zombie ~ ~2 ~ {DropChances:[1.0f,0.2f,0.2f,0.2f,0.2f],Equipment:[{id:272,Count:1,tag:{display:{Name:"Undead Knight's Sword"}}},{id:301,Count:1,tag:{display:{color:8882055}}},{id:304,Count:1,tag:{display:{color:8882055}}},{id:299,Count:1,tag:{display:{color:8882055}}},{id:298,Count:1,tag:{display:{color:8882055}}}],CustomNameVisible:1,CustomName:"Undead Knight"}

And one that doesn't:

/summon Witch ~ ~2 ~ {DropChances:[1.0f,0.2f,0.2f,0.2f,0.2f],Equipment:[{id:387,Count:1,tag:{title:A word from Aero,author:Aerotactics,pages:["Good Riddance."]}},{},{},{},{}]}

And have no idea why code 2 doesn't work.