You might have more than one file that is named index.php. Look into the other file you're redirecting to and show that code. It doesn't help to ask about the wrong code.
In case anyone else runs into this issue like I just did, it's an encoding issue. When editing the file in Notepad++ it looked fine, but in regular Notepad there were no linebreaks. You can either add the linebreaks using notepad, or change the encoding style to match your server (UTF-8 without BOM is probably what you want).
index.php. Show some codes from yourindex.phpinsteadphpinclude()which - surprisingly, doesn't exist.index.php. Look into the other file you're redirecting to and show that code. It doesn't help to ask about the wrong code.