Canni + Insta-click question

[Spacebar]

I just wanted to check I was understanding this right. Basically I got a Kromzek Scope in hopes of spamming Cannibalize. I'm not sure if I'm just not doing it correctly or if I misunderstood the way this was supposed to work.

Here's what is happening:
1. I cast Cannibalize (canni 1 currently, I'm lvl 34)
2. I instantly right click scope to refresh global
3. Global refreshes, all other spells can be cast but cannibalize is still on cooldown so I can't immediately cast right after global refresh

I just wanted to make sure I was doing this correctly and also if maybe I just misunderstood the purpose of an global cooldown refresher with cannibalize.