Beast Tamer Gem not working?

I've been trying to play with the new huntress ascendancy but once i got my first tame beasts skill gem I just cant seem to get it to work. The animation of the enemy getting effected by it does not happen. I've made sure its a beast i'm attempting it on. I've made sure i've got enough spirit also but it will not work no matter what beast i've attempted. Has anyone else been unable to use the gem or am i missing something?

I have been doing it and stocked away all the Unique beasts. You have to use it when the Rare or Unique is near dead. It has a small window and if you wait longer the the 10 seconds it will lose the debuff and you will not get the beast.