Items sharing Ability Cooldowns...

I'm trying to make it so that- when a hero has an ability and does it's effect and having an item with the same ability, but with a slightly weaker effect- the hero ability and the item ability will share cooldowns, so people can't spam one, then the other.

I've tried giving the item the same cooldown group as the ability, but for some strange reason, they still don't share cooldowns. Am I doing something wrong? Did I miss something?

Thanks in advance.

Well, the thing is, you cant set cooldowns, so no you cant share them.
There is a work around with timers, starting the timer when the ability/item is used, for its cooldown time, and if the item/ability is used while the timer is running, stop the effect.
But this wont have the visual blackned effect that goes around the icons.