This is very frustrating and happens to almost everyone from time to time. This is what I do --- I press my fabric --- make certain I have a straight grainline (I think this is rather important) ---- fold as needed -- then I press the fold (no steam, just hot iron) -- apply pressure on the ruler and make sure you are using a sharp blade in the rotary cutter. Then I carefully unfold the fabric and press out the fold line I made earlier. (a dab of water can help ease out the fold line) This may be right or wrong and I'm sure you will hear from other board members ---- I'll be looking for new tips, too. :)