How do I copy and paste polygons for lengthening a road?

[PhilPreston]

Hi All,

Currently editing a track with T3ED 4.5.0.436.
Have been able to copy blocks onto the end of an open ended road.

But when I try to copy and paste a polygon, or multiple polygons nothing happens. 
Can someone tell me what I'm doing wrong?

Also, the New/Split Polygon function only seems to work in one direction.  Is there a way to switch it so it splits in the perpendicular direction?
Sorry, I'm totally noob with this editor

[JimDiabolo]

Splitting black polygon works only to the sides. This is because each block contains a maximum of 8 polygons in the driving direction. This is the same number as the VRoad points.