Probably easiest to say that just about everything directly related to how your trying to paint the walls is not correct. Here’s a script that I wrote a while back for the same kind of thing that you can look at and try to evaluate how it differs from yours. This isn’t the most robust script as it will fail if you don’t have a list (single object), or you have a multi-dimensional list, or if you have a face based wall, but it should be enough to get the point across.
-Tim