Succubus lesser invisibility

The spell does not always work.

When you login first time and instantly use the lesser invisibility on your succubus, it usually tends to work. After second time, it will keep on saying that the succubus is in combat, and cannot use it (spell id: 103140)

This case also applies to

Spell Lock
Devour Magic of Fellhunter and

Fire Shield of Imp, sometimes it works but sometimes it simply says you are in combat