I recently attempted to install a low retaining wall, about 10' in length. I used 1' long pavers, leveled the area with paver sand, then individually leveled each paver as I went. Somehow it still came out sloped. I didn't measure to what degree, but it looks to be about 2 inches off from one side to the other. I don't get how this happened, but would welcome any advice on how to do this with a better result.