RSS looks damaged

You’re right, that feed does not look so good. Do you have any other plugins installed, or anything else than could interfere with my plugin somehow?

I just checked the feed from some of my sites using:
https://validator.w3.org/feed/

and they are all ok. so… something on your side messes things up, I think…

hmm. you are right! as far as i deactivate my own plugin, it works. but my plugin is very simple. therefore i dont see any problems right now. file is UNIX and UTF-8.
Here you can get it: https://dl.dropboxusercontent.com/u/139690/wps-fbapp.php

Whats wrong with that file?