ToME: the Tales of Maj'Eyal

My current Temporal Warden is exploring Tempest Peak.
When I try to activate Premonition (sustainable talent), it self-deactivates.
Any ideas why it would do that ?

Either no mana, or a spell failure chance.

This one uses Paradox, so it's not about mana.
Speel failure could be, but with my current paradox level, I have a 1% chance of failure. It will unlikely fail several times in a row.
Moreover, when spells fail because of Paradox, there are some special effects (and a warning message). I don't have such effects nor warnings. That's why I wonder what's happening.

That's not the first time BTW. I already had this problem. Are certain levels or dungeons auto-deactivating some spells or talents ?

Ooops, my bad, you are right : Premonition does use mana and my character has no mana left.
It was really a dumb question