I have a lv 4 paladin and I can’t use effectively. The spell say that recover the paladin lv * wisdom modifier. Even my paladin lv 4 with 4 wisdom modifier heals only 1 hp instead of 16.
Does anyone knows anything that helps me understand why it ia only healing 1 hp?

What module or campaign are you playing?
What version of NWN EE are you on?
Do you have anything in your override folder?

Normally it should work like you say, and it does work for me on v79.8193.5, so either something broke in the new patch, in case you're using that (Galaxy?), or it's something in your override folder (make a backup and then remove its contents), or it has to do with the module you're playing (like a PW with special rules?).

The modifier is CHARISMA not Wisdom
See the owners manual

Maybe I've had too much rum, but I read that as the paladin needing to smile more, haha!

Oh, right, that too, heh. *blushes*

But if that's the problem here, it must mean that the OP's CHA modifier is 0 or lower, otherwise the OP would have gotten at least 4 hp back, not just 1. And I think CHA is important for a paladin in general, isn't it? It shouldn't be just 11 or lower, right?

It actually has several, they're just split across different websites (GOG, Steam, Beamdog, NW Vault etc.). GOG's is rather small in comparison, but all the better that you're still able to get answers here, too. :)

Lay on Hands.

From Character Creation Menul

" With this feat, characters can heal danage equal to their Class level
MULTIPLIED by their CHARISMA modifier

In AD&D, a paladin had to have a minimum CHA score of 17 to even qualify to be a paladin!

Lesson: Don't use CHA as a dump stat for paladins (or bards,or clerics).

[deleted]