Modern Greenway

Why do the stairs not appear?

I used it somewhere else in my city and it worked, but I decided to replace that one with the brick version. 

When I've used the Modern Green somewhere else, it's not showing the staircase. I'm using 4 sections, the same as before, and crosses a road and railway. If I take a piece away and put it in open space the staircase appears, but when I reconnect to the other three sections I have no staircase. It's the same thing at both ends.