wordpress - Plugin admin settings not saving in network admin level only -

add_action( 'admin_menu', array( &$this, '_settings_menu' ) ); add_action( 'network_admin_menu', array( &$this, '_settings_menu' ) ); 

i'm using [admin_menu] , [network_admin_menuu] actions create option pages plugin , saving operations working great in wordpress multisite blogs.

but, in network admin level [ /wp-admin/network/admin.php?page=plugin_settings ] not [ /blog-1/wp-admin/admin.php?page=plugin_settings ]

after saving page redirect [ /wp-admin/network/options.php ] , following error appears , of course won't save test values.

object not found! requested url not found on server. link on referring page seems wrong or outdated. please inform author of page error. if think server error, please contact webmaster.

the plugin activated under network