Caching Problem

I like to cache my page with

public function filters() {

        return array(



                'duration' => 60,

                'varyByExpression' => $this->region,

                'varyByParam' => array('id', 'region'),




It worked fine, but I have different pages when changing the parameter $this->region.

Its a global parameter in the Controller.php. This parameter remembers my current location:

One page is for New York, the other page for Los Angelos. When giving the paramter in the URL: it is fine and the page for New York is loaded, but when I only have (and Los Angelos is in the cache), then the page changes to Los Angelos, although in $this->region is New York.

I hope somebody wil understand this :) and can help me…