Sketchucam won't accept outside cut tool

I’m using Sketchup 15.1 and the extension ‘Sketchucam’.

Everything loaded correctly, but after I flattened the graphic I tried to use the outside cut tool but the graphic goes gray. Also when I move the 'Outside tool towards the graphic the vertical line to the left and the base line turn red.

I’m doing something wrong but I don’t know what.

Please watch this video and then read the help (blue question mark in toolbar)