Help: Heart Of Llevigar

I am trying to do the quest "Heart Of Llevigar".

After talking to Zenam, he tells you to go to the Head Engineer in the Power Plant.

The entrance to this powerplant is across from the bank of Llevigar.
You push a button and you drop down into the Power Plant.

Here's the issue:

When I drop down it says "You hear a humming sound, you shouldn't go inside" and teleports me out...

Am I doing this correctly? The Wiki says absolutely nothing about the entrance except that you should enter it.
Am I supposed to do another quest before this one? If so, which one?

 

Hmmm maybe try talking to Zenam again? Sometimes my questbook doesn't update properly and I have to talk to the NPC twice.

 

last time i checked i did this speedrun multi times for this quest, i dont think this quest are any related to any other quest, the whole purpose is to speak with npc (but i might be wrong but he might be pirate trove npc before you see him again ) and click button will drop you down to basement then you speak npc B to start solve the puzzle.