The problem you see is due to the height of the inner panel which is by default 500.
If you set it's value to 1000 it will fill to whole screen.
Instead of using the code below in the DesignerScript: ScrollView1.SetLeftAndRight(0%x,100%x)
ScrollView1.SetTopAndBottom(0%y,100%y)
You can remove it and make the ScrollView fill the screen in the Designer and set the anchors to both.