Vertical Gore Tool

I am designing construction crossovers on the interstate and I am having problems using the vertical gore tool.  Everytime I create the finished surface it fails to clip the ramp to the mainline it still shows the ramp edge and end conditions on the mainline.  I have followed step-by-step instructions per the Bentley Vertical Gore Tool on demand video.  The only conflict I have with the video is that when creating the finished surface the instructor picks two surfaces in the target aliasing box and then creates the finished surface applying the clipping options.  When I pick two surfaces there are no options to clip.  When I pick one surface and one corridor, then I have the option to clip, but it never clips correctly.  Any information would be helpful.  Thanks.