I am installing 5 1/2-inch baseboards on a tile floor and dry-walled wall. I am using an 18-gauge nailgun and 2-inch nails. When I place and nail the baseboards, there are intermittent gaps at the top of the baseboards, and they dont seem to be secured to the wall very well. I initially was nailing near the center (height-wise) of the baseboards, but since they weren't very secure, I began nailing near the base, but there are still gaps at the top of the baseboards. I have installed the standard baseboards before and not had problems.....I am considering scrapping the 5 1/2 inch boards. any suggestions?