Hi again.
I´m SO sorry that I answer you so late. I simply didnt see your answer before now.
It works on my curve from the landscape.
So THANK you very much for your help 
I first tried just to create a simple curve, convert it and run your script. But that didnt work. The script couldnt register the curve. Do you know why ?
And one last thing. Can you tell me how I can fing the total length of the curve?
I have som focus point on my route that I would like to show on the unrolled curve. So I propably have to divide it in more pieces to do so.