Vim syntax based folding with php

Question

I have downloaded php.vim file, which contains PHP-based syntax information. It should be able to provide syntax based folding, but I can't make it work for some reason.

I have set :let g:php_folding 2 and :set foldmethod=syntax but for no avail. I'm pretty sure the file is in right place and is read by vim, since I can do :let g:php_sql_query=1 which works.

The php.vim file is located in ~/.vim/syntax/php.vim