Mages and scripted spells

[Herode]

Hi gentlemen,

I'm trying an EA game with T'ien C'hi. Some heroes joined pretty soon in the battle, and amongst them the Immortal Ho Hsien-Ku (A2 N3). I scripted Ho Hsien-Ku with False Fetters (requires A2 and no gems). Nevertheless, during the battle, HSK never casts this spell but prefers other ones like Air Shield (and that's a real spoil as Air Shield comes with the bless...), Howl (pretty wolves, almost useless against my actual opponent Helheim...) and so on, making her of little use. Moreover, she consumes her nature gems and that's not what I want right now.

So, my question is : why doesn't HSK follows the scripted orders ????? (PS : of course, I have unlocked False Fetters with the required amount of research).