Changing edge color of a box with groupSOP and pointSOP

Hello, first post here.

I think a picture is more explicit than words.

As you can see, i used groupSOP to select some points, (wish i can select an edge).
Then i refer my group into the PointSOP, to apply just the color to this edge.

But the result is very weird.

Any help, please.

(i fed the groupsop twice in the pointsop cause i was trying everything)