Never put a "once-only subpattern" (?>...) in a "one-line" comment (#, //).
I spent almost 1 day to fix it.
Use a 'C' style comment instead !
PHP Manual says, a "one-line" comment (# , //) ends just before "?>" (PHP end tag).
These letters "?>" in a "one-line" comment (# , //) seems evaluated as a PHP end tag.
<?php
/* (?> */
echo '"C" style comment works !<br>';
# (?>
echo '"one-line" comment';
?>