Open CV Callibrator

Hey guys!
Pretty new to Unreal Engine and sadly there isnt much documentation on my problem:

Im desperately trying to find my 3d lens distortion data. Ive tried looking around and most of the time the “simple” tutorials look pretty baffling to me.
Then I looked into the unreal documentation and there is a node called “CV Open Callibrator” which seems to be doing what I want. The endresult being the k1, k2, p1, p2… components of my camera. Calibration | Unreal Engine Documentation

Now there isnt much documentation on how to get it running but it seems so simple that I must be missing something.
you can create a callibrator insert checkerboard WxH and box size, you can feed it images (paths to files), if it has enough data it send the result.

Here is the setup of what Ive been trying to do:Imgur: The magic of the Internet
Anyone got any ideas of what I could be doing wrong or whats missing?

So you don´t understand post process effects or what happens exacly just that does not work ?

Mhhh, Would it being a post process material change the workflow I posted?
I mean I can’t find “what” it is, I just assumed it would work in an event graph. But it doesnt find checkerboards in the images as if there are components missing. But everything in the documentation I put in the blueprint aswell.