I can't progress my walking through on chancel

[BraveCookie]

Hi
I'm really enjoying your game : Amnesia The Dark Descent but I have an problem
I was progressing my story until chancel.
But I couldn't solve what should i do after pouring tar into the long barrel.

So I searched 'Amnesia Chancel Walking through' and i watched this : [https://youtu.be/ozT7THlq5i4]
and then the youtuber said when you get in the chancel, you will face the grunt and you should hiding any location.

For some reason I couldn't find grunt in any way.
In the comment down the video, I could see a comment that :

'[color=rgba(255, 255, 255, 0.88)]Looking at the map file, the grunt is there when you enter the map for the first time (if you leave and come back, he will disappear because that's how Amnesia works) and he comes to the entrance and despawns (goes to the Nave).[/color]'

And a reply on another comment said like flashback might disappear grunt...
I've tried many times to encounter grunt but i failed... What should I do?

[Romulator]

Have you visited the other locations in the Nave area? You need to collect Orb Pieces and place the Orb Pieces on the pedestal where you put the bucket of Tar in.

The Orb Pieces can be found in the Choir and the Transept areas.