At the risk of sounding presumptuous, be very certain of two things...
1. You put the PHP-termination characters ?> at the very end of the file and it looks like the sample above. There should be no spaces, no new-lines, NOTHING after the ?> characters.
2. You actually REPLACED pluggable.php on your server after editing it. Completely exit your FTP program, start it up again, browse to the location and open the file from the server to make sure!
People can get confused about local vs. remote files with FTP and while you may edit a file locally and it all looks good, you really need to be sure that those edits made it back to the server or you will have done nothing.