I don't know what causes it, is it an update that I haven't found out or something? Sorry for bad english though, I hope it doesn't matter.
When I try typing /summon Fireball (or SmallFireball and WitherSkull) It gives me text "Unable to summon object!" wich is really annoying, since I'm using them a lot, when working on my Vanilla Wands- project. And yes, I want to get it 1.9 compatible, so I can use it later in my 1.9 maps that I'll make. If it's not a glitch, I'd like to know how to use the new system (if there is one).