Game Mechanics: Orb of Tishan Proc not Stacking with charm

[Jete]

http://everquest.allakhazam.com/db/item.html?item=84 ( Orb of Tishan link )

Name says it all.. Back in the day I use to proc orb then charm something... on this server however it says "Spell will not take hold," after proccing the orb.

- Edit/update
I believe the issue is that Tash itself doesn't stack with the MR ressist debuff that is attached to the lvl 39 Bard charm ( Solon's Bewitching Bravura ).

Both on live and in classic this stacked, or at least the proc from this weapon did because that's how I used to charm. Malos is currently stacking with charm which is correct, but tash however, is not.