Hi Kevin, the surfaces have too large of a gap between them to join, it seems to be that at least one of your profiles over here is a fair distance away from the rails:






Maybe that profile got dragged over a little bit accidentally or something?

Try deleteing the current sweep, drag that one errant profile over into place (grab near the end with object snap and straight snap active and then go over until you get an "int" snap on the rail), then redo the sweep and it should then join in ok.

I did a quick check of the other profiles and it looks like all the others are ok, it just seems to be that one that's out of place.

Hope this helps!

- Michael