Blubsi on "Using wp_editor in "own" Plugin"

Thanks alot for your reply bcworkz!
For everyone who encounters the same issue:

function setting_editor_fn() {
$options = get_option('plugin_options');
$args = array("textarea_name" => "plugin_options[textarea_one]");
wp_editor( $options['textarea_one'],"plugin_options[textarea_one]", $args );
}

Don't forget to:

add_settings_field('editor', null, 'setting_editor_fn', __FILE__, 'main_section');