Hey, I'm sorry, maybe you can see, what I did made wrong. I did have made a small screencapture-video - it's just a question - HOW TO USE the PLANAR SECTION

http://www.mediafire.com/download/e6w3m98ex4y0k48/test-planar-sections.3dm

http://www.mediafire.com/watch/5q4xp8qs3016eic/Blend-Planar-Sections.avi