Just for tests, I'd make sure that your cache isn't stuck. Since your getting zero output in either the default header or footer. Try FTPing into your site and go into the templates/compile directory and delete everything except for index.html file.
I put the same include into my test board, and I didn't get any output from it either (because it doesn't output anything if some conditions aren't met. I was able to add an "echo 'test';" right before the closing php tag though and I did see that.
