Stripmining turtle - doesn't work.

print("How many rows?")
rows = tonumber(read())
leng = 10

function OneForward()
  while turtle.forward() == false do
    turtle.dig()
  end
  turtle.forward()
  while turtle.detectUp() do
    turtle.digUp()
  end
end

function digleng()
  for j=1, leng do
    OneForward()
  end
  turtle.turnRight()
  turtle.turnRight()
  for j=1,leng do
    turtle.forward()
  end
end

for i=1,rows do
  OneForward()
  OneForward()
  OneForward()
  turtle.turnLeft()
  digleng()
  digleng()
  turtle.turnRight()
end