Rampage not woking on Mercenaries

Mercenaries is equip with Gravebind Hydrascale Gauntlets and a Rampage item, but when killing mobs it doesn't start Rampage for the mercenaries. Note tried all Rampage Items, but still same result.

Which mercenary archetype, and what kind of build are you playing?

I've not tested the Rampage mechanic with mercenaries, but my first thought is that you might be overestimating the rather modest range of Gravebind.

Mercenary is a Sniper and im just trying to see if bisco's leash would work on the Mercenary. Just thought it would be nice to hv it running rarity for items found.

As for rang of killed enemy i had a group of mobs group up on me b4 killing them and the only thing i saw that went up for the Mercenary was its movementspeed, but the rarity didn't go up and the Rampage also didn't start up too.