Hi Janne, it looks like we posted some messages at the same time so you may not have seen my very last one - check it out here:

http://moi3d.com/forum/index.php?webtag=MOI&msg=3431.4

That shows some more illustrations for how you would want to position the profile to get what you want.

I've also attached a model file here with the profile positioned how I think you want it - try sweeping the profile in the attached 3DM file to a result that goes towards the inside of the rail, because the profile is touching the rail and positioned to that side of it.

- Michael