CodeIgniter WURFL API Wrapper Library

[eluser]Unknown[/eluser]
i got problem with wurfl my instalation looks like above:

main folder:

app -> application
-->config (wurf-config.xml)
wurfl-> wurfl.xml and web_browser_patch.xml
cache-> cache folder with (777 mask)

in wurfl-config.xml i got (i tested with relative path too):

Code:

<wurfl-config>
    <wurfl>
        <main-file>../../wurfl/wurfl.xml</main-file>
        <patches>
            <patch>../../wurfl/web_browsers_patch.xml</patch>
        </patches>                  
    </wurfl>
    <persistance>
        <provider>file</provider>
        <params>dir=../../cache</params>    
    </persistance>
    <cache>
        <provider>null</provider>
    </cache>
</wurfl-config>

in app/libraries i got lib for CI Wurfl.php and other wurfl php files.

in controler i got just:

Code:

function Welcome()
    {
        parent::Controller();    
        $this->load->library('wurfl');
        $this->wurfl->load($_SERVER['HTTP_USER_AGENT']);

    }

and as result i receive this:

Fatal error: Uncaught exception 'Exception' with message 'Did not expect element persistance there ' in /usr/local/www/apache22/data/dev/plabudz/m/app/libraries/WURFL/Configuration/XmlConfig.php:77 Stack trace: #0 /usr/local/www/apache22/data/dev/plabudz/m/app/libraries/WURFL/Configuration/Config.php(47): WURFL_Configuration_XmlConfig->initialize() #1 /usr/local/www/apache22/data/dev/plabudz/m/app/libraries/WURFL/Configuration/XmlConfig.php(43): WURFL_Configuration_Config->__construct('app/config/wurf...') #2 /usr/local/www/apache22/data/dev/plabudz/m/app/libraries/WURFL/Configuration/ConfigFactory.php(11): WURFL_Configuration_XmlConfig->__construct('app/config/wurf...') #3 /usr/local/www/apache22/data/dev/plabudz/m/app/libraries/WURFL/WURFLManagerProvider.php(72): WURFL_Configuration_ConfigFactory::create('app/config/wurf...') #4 /usr/local/www/apache22/data/dev/plabudz/m/app/libraries/WURFL/WURFLManagerProvider.php(59): WURFL_WURFLManagerProvider::_init('app/config/wurf...') #5 /usr/local/www/apache22/data/dev/plabudz/m in /usr/local/www/apache22/data/dev/plabudz/m/app/libraries/WURFL/Configuration/XmlConfig.php on line 77

please reply to me if you can help it is very important to me to get Wurfl work together with CI.