[marco_kellershoff]

I'm not familiar with wordpress, so I don't really know what wpHeader() is doing.

If it is just returning the header html like so:

PHP Code:

return $wordpress_html_string; 


then you need to alter the extension's code a bit like this:

PHP Code:

    public function wpHeader(){
        define('ROOT_DIR',str_replace('\\\\', '/', realpath(dirname(__FILE__))).'/'); #Get real path for root dir ---linux and windows
        require_once(ROOT_DIR.'../beta/wp-blog-header.php'); // get WordPress  
        return get_header();
    } 


(now the function returns the value)

and then in your template you do something like this:

{vb:data wp_header_html_string, wpHeaderFooter_Api_Options, wpHeader}
{vb:raw wp_header_html_string}

the first line just assigns the data and the second ones echos it

--------------- Added [DATE]1379249675[/DATE] at [TIME]1379249675[/TIME] ---------------

You might also want to read about this related topic here:
http://stackoverflow.com/questions/1...-a-text-string