Loft tool error: Rail is not smooth

[zeromxx]

On the sketch, all the lines are connected, and they look smooth. However, when I try to do Loft, the error "Rail is not smooth" appears. Is there any solution? I've also attached f3d file as well.

[davebYYPCU]

Firstly, Loft half and then mirror the 2nd half.

Your Rail appears to have selected the centre line as part of the chain select.  The intersection between the curve and both ends of the centre line are highlighted red because they are not smooth connected.

You can not make the Loft you want in one go because the rail is not a single smooth sketch article, and Rail must connect to ALL profiles for success.  Your half Rail only intersects with 2, 3 and 4.

I don’t have access to your file. 

Might help....

[TrippyLighting]

Is this a real object you want to model, or just a test?

I would advise against mirroring in an entire sketch. I would definitely not mirror a fit point spline.

[TheCADWhisperer]

I would clean up the sketches - you have lines overtop of lines (I dragged to show) and unconstrained.

(So all lines are NOT connected.)

I am not sure this is what you want.

Toggle anything that shouldn't be part of your model to Construction.