Error with helf_vhp

Add in the constructor (line 30) :
define("helf_vhp",0);

public function __construct() {
		define("helf_vhp",0);
        add_action( 'init', array( &$this, 'init' ) );
        //add_action( 'admin_bar_menu', array( $this, 'varnish_links' ), 100 );
        add_action( 'rightnow_end', array( $this, 'varnish_rightnow' ) );
    }