Thanks for visiting my farm. When you are stacking either the logs or the crates, they will stack on each other as long as neither one is not touching something else. An example is my rock wall and the hedges that were behind the garage before I moved it last night. As the roof progressed further away, it started refusing to stack. "Dirt" is your answer. It's under Paths. On my farm, you'll see lots of used dirt that I've tried to hide. When something won't stick, you place a piece of dirt on top of the item beneath. You have to do this at every spot. This is true also of flowers and trees. When it won't allow you to place them where you want them, use dirt to layer between. I hope this helps. It's hard to explain. If you haven't visited this website, do so - it will help you understand. - written by some of the best and most talented people in Farm Town. Good luck.
Diane