I know that in this case I have to be precise in picking the curves and did that.
The rail is build from a straight line and two tangent radii.
If the rail is fix loft and rebuild does not help.
Thanks @pascal how you found the blue curve?
´refit rail´ works but why it is not nice?
I work around in this case by split the red curve and build the front part with sweep2 (sweep1 also does not work). Other solution I can see is to ad a second rail curve at the other side of the green ones.
Andreas