How to add 2 columsn

Hello everybody.

I am just update my plugin and I am not able to set 2 columns on my option page… what is wrong with this code?

add_filter('screen_layout_columns', array(&$this, 'on_screen_layout_columns'), 10, 2);

and then:

function on_screen_layout_columns($columns, $screen) {
		//for WordPress 2.8 we have to tell, that we support 2 columns !
		if ($screen == $this->pagehook) {
			$columns[$this->pagehook] = 2;
		}
		return $columns;
	}

it does not work ?? thx a lot.