I have been working on a file from the Rhino Version 4 training manual Level 2 chapter 8.

I was mirroring tapered surfaces from one side of a supposedly symetrical 3D surface.

When I tried to join the surfaces on the side that I mirrored to, the join would not take.

The join was fine on the originating  side. 

I decided to take a top curve from the  originating side and mirror it for the cut out on the left.  Then I intersected the curve with the surfaceand it says there are two intersections, but the intersections are not showing up with a point.  Is there something in my display to make them show up? How do I replace the curve to make it proper so that I can cut it out and mirror the tapered surfaces for a join?