rail and extrude problem

 From:  stan
hi everyone!

really great program. some of my collegues (in architecture) are already using it, as well.

the first real problem ive got so far has to do with a gap i get when i try to extrude a closed spline or do a rail along a spline.

the solid object i get out of extruding is supposed to be bend. when zooming in closely it turns out to be kinda straight though. am i doing something wrong?

i attached some image that shows the gap.

thanks in advance stan