div regexp

[gilgalbiblewhee]

I'm trying to figure out:

preg_match_all("(?<=\<div style=\"direction:rtl\">).*(?=\</div>)", $file, $content); 

I want the innerHTML of a div tag which has the style direction: rtl.
It's giving me this warning:

Warning: preg_match_all() [function.preg-match-all]: Unknown modifier '.' in C:\...\index.php on line 42