Why Enlightenment not always works?

[asd090]

Only one of casted Enlightenment spells has effect.

No icon on avatar of hero and no effect, nothing happens, like I didn`t cast enithing.
What is the cause of the problem?
Is it because heavy armor or low charisma?

Thanks.

[Androdion]

Enlightenment works. When you cast it a small icon with scroll image appears near your avatar's portrait. When it wears out you can cast it again.

The effect of the spell is to temporarily increase your Int and Cha stats.

[mordo]

It happen to me every now and then that i have to re-cast it a few times until lit, try walk a few meters before re-cast, works for me.