I did this pattern too. When I sewed Row 1 to 2, 3 to 4, etc. everything was great. When I sewed row 1&2 to 3&4, etc. I started getting peaks and valleys. WHAT did I do wrong? I was really watched carefully so that the biased sides didn't get stretched. Any and all help would be greatly appreciated as it now in my UFO stack since I had difficulty with it.