Looking at the video, I do notice one issue with the inputs: you use "topEjemplo.png" as your palette input, but it looks like that image is wider than 2 pixels. Use another, small image (it can be 1x2 pixels of the same colour, if you don't want it to change anything) and see if that will work. It should show the preview image when you click on "Save Output" and it doesn't, meaning the tool couldn't make one, for some reason.