affected on skill stats is not working?

I tried to make a spell with the option "effected" as I noticed in other spells.

I tried:

affected detect invis 10(duration)
afffectd invis 10(duration)
affected hide 10(duration)

but nothing of these worked

I made many tests among my characters.
The spell effect appears on character but the result is not as it had to be.

Strength, mana, hit etc work fine

Do I do anything wrong?

We can't know what you did wrong unless you link to your code.