Rostock pen test print problem

Hi there,
This is a pen test of my new built Rostock 3D printer.
I used pronterface to draw 10 mm squares on the paper but as you
can see the result is horrible!
I built my Rostock based on the original design and used Marlin firmware and double checked everything including mechanic and electronic parts,but it seems that the problem persists.
Any suggestion would be appreciated.
Thanks in advance