I make a first line (clic at start point, choose direction with mouse, type length on keyboard (20) then enter) ok. When I make a second line the same way, with 50 as length, the actual lengt will be 5020! the new value is added to the left of prevous one! 

If I make a third one of 10, length will be 105020! 

Doing esc or enter between lines or exiting the function dont't solve the problem. 

Help! Thanks

example here : circle of 10, then circle of 10, ten line of 10. 2nd circle is actally 1010 and line 101010