My level 15 mage has his staves skill up to 87%
He has no problem brandishing defensive staves.
But every time he tries to brandish an offensive spells staff,
he "fails to invoke" it. This is true inside or outside of melee,
against mobs. Given the 100% fail to invoke rate, he hasn't used
any in pk. An immortal on newbie channel suggested this was because of
a level issue, i.e. the staves are too high of a level -- that made
sense with the one I found in a hidden spot in a high level area. But
now, all the ones I'm using I've found on mobs and some of them I've
bought. I figure if my character can kill the mob solo at level 15 or
buy the stave, it can't be too high a level for the character.

I'm really frustrated by this, and it seems a game mechanical issue.
Does any one know what's going on?