What is a flat edge pattern?
As others have said - your sub- units of the block need to be the same size ( the four- patch and the triangle- in- a- square units)
I think the triangle-in-a-square unit is tricky to assemble properly. Something that helped me a lot was to draw the seam lines on the triangles and pin at the seam intersections. The edges/ears/tails are not even.
I am using my nook right now , so can not refer to anything.