Hmm... I think it's because you have cut out that part of the scene. The horizontal/Vertical scroll borders are used to set the playable area of a scene, if I remember correctly, so I'm not sure what you are trying to achieve with them.
If you are wanting to adjust the amount of distance from the edge of the screen (current viewport, not entire scene) the character has to be to trigger scene scroll then you can use these 2 lines of Lua script.
-- set distance from viewport edge (in px)
game.HorizontalScrollDistance = 100
game.VerticalScrollDistance = 100
What you have done with those action parts is define the scrollable area...
Usually the scene can be scrolled to the edge in each direction. This area can limit the scrolling in each direction so the scene can not be scrolled to the edge.