RVXLiverSegmentation extension questions

I am trying to use your 3D Slicer RVXLiverSegmentation plug-in, but I have some problems:

i) I specified all portal vein nodes. Why does the button “Extract Vessels from node tree” continue in gray color without activating it?
ii) When I was trying to specify the nodes of the vessels, I tried to view the “node position help window”. But, that window appears completely white color. Without any tree vessels. Why?

Sincerely,

Gonzalo Rojas Costa