PHP Code doesn't work

PHP Code on works now with very simple code:
Pattern: /foo/'
PHP: On
Replacement:

if($matches[0] == 'foo')
return 'bar';

But none of the examples in the documentation or similar more advanced code seems to work.

After hours of working with this module I run into this situation:
Some Patterns with PHP Code replacement works with 6.x-1.0-rc2 on my localhost but not on another machine with the same setup (Drupal/PHP)

Some Patterns with PHP Code replacement works with 6.x-2.x-dev, but not with 6.x-2.0-beta 7.

In neither version all Code samples from the documentation pages works. I've also tried some samples from Version 5.x (Wiki samples). Same situation: one works another not.

But in 6.x-2.x-dev one cannot edit any rule (blank form for existing rule)
See also: http://drupal.org/node/685584

I believe this is a very, very usefull module, but a little bit buggy.

The example code is probably not updated with the latest developed code; for sure it doesn't work with branch 6.x-2.
For sure?
On my localhost I run the lastest 6.x-2.x-dev version with example code from the 5.x Version of your module.
Pattern: /^(\={1,9})(.*?)(\={1,9})$/m
Code:

$len = strlen($matches[1]);
          $result = $matches[2];
          if (strlen($matches[3]) == $len) {
            $anchor = count($vars->headings);
            $vars->headings[] = array(
              'level' => $len,
              'text' => $result,
              'anchor' => $anchor,
            );

            $result = "<h$len><a name=\"$anchor\">$result</a></h$len>";
          }

          return $result;

And it works!

And of course I don't work with a dev Snapshot on a production site.