I made a large circular shaft on a server, 32 blocks in diameter. I placed drawbridges around the edge, so when they are powered, they extend and cover the shaft completely. This worked fine in SP, but when i made it in SMP, there were holes randomly in the cover the drawbridges had placed. I tried to wire the drawbridges to turn on with a delay between each one, but it still didn't stop the holes from occurring. The drawbridges had enough blocks, and it seemed like the holes were completely random, so i think it was due to server lag. I had made a smaller door, a vertical blast door using 20 drawbridges, and that worked perfectly without any errors. This one had 60, but even staggering the firing of each drawbridge did nothing to change the lag. Any suggestions to fix this?