PHP+HTML with mmm-mode

[ignat . skoryh]

I'm trying to setup my emacs to edit PHP code with mmm-mode. I was
able to make it switch to different major modes (html and php
accordingly), but it fails to highlight embedded php code correctly,
as you can see on the screenshot: 
http://www.javaparts.com/dst/emacs-html-php-mode.png.
As you can see mmm-mode adds background color around php regions, but
inside those regions keywords (e.g. if) are not highlighted. What am I
doing wrong?

Here is my .emacs initialization:

;; Use HTML mode for php files
(add-to-list 'auto-mode-alist '("\\.php$" . html-mode))

;; Load MMM
(require 'mmm-mode)
(setq mmm-global-mode 'maybe)
(setq mmm-submode-decoration-level 2)
(set-face-background 'mmm-code-submode-face "gray15")
(mmm-add-classes
  '((php-in-html
      :submode php-mode
      :face mmm-code-submode-face
      :front "<\\?\\(php=?\\)?"
      :back "\\?>"
      :include-front t
      :include-back t)))

(mmm-add-mode-ext-class 'html-mode "\\.php$" 'php-in-html)

;; Colors
(global-font-lock-mode t)

Thanks!