I found my problem using another tutorial video from Youtube.
What wasn't explained in the video I used is that the model has to be subdivided. In the video, the object is already subdivided many times.
In my case, I just had to select N x N FFD, add my grid size and select subdivide!

Thank you for your answer TIG.

Ok, after I set that parameter of, now I can see the cylinder.

But moving the dots with the scale tool still has no effect on the part.
I'm doing exactly what I found in that tutorial video, except I work on a simple cylinder.
https://www.youtube.com/watch?v=sBLX1SFKULU&t=13s

Hi,

I'm trying to use the plugin, but the part I try to modify disappears when I double click the dots.

Example, I draw a cylinder, make it a group, apply 3x3 FFD, and when I double click one of the FFD dots, the cylinder disappears.

Am I doing something wrong? Using sketchup 2017.

Thanks for reading