Clip corridor at civil cell

I'm using Power Geopak V8i SS10. Very new user.

I am trying to clip my corridor at the basic T civil cell I have intalled, I thought I could just mask my corridor but the intelligence will still be there and show up at on my proposed cross sections. After reading forums it appears as though in project explorer you can go under civil cells, right click terrain model and select "Add corridor clipping boundary". When I do so, nothing happens? Is it because my terrain model is not the correct/active one? All of my civil cells have Terrain Model as: Side road Pvmt, which is where I had civil cell tie to.

Just trying to get my corridor clipped so my cross sections don't show sidewalk going through the intersection.

Thanks for the help!