Animate Guardian - how does it work?

Hello,

I found the skill gem Animate Guardian today and equipped it into my helmet. I wanted to animate a claw I found. I identified the claw and threw it back to the ground but when I select it and press the keyboard shortcut for the cast, nothing happens except the mana drain.

What am I doing wrong?

Regards

The claw was probably of too high item level, the limit will increase by levelling AG gem.