Board Thread:General Discussion/@comment-10292226-20131008080024/@comment-24025262-20131008130400

I could be incorrect but I am just making a prediction in hopes of being some help. First their is a lot of stuff on your background so it could be you are missing some background walling, as it has to be filled in completely to be valid. Another possibility is that some of them have do obstructions, such as things that make it hard or impossible to close, though that may not be a requirement at all.