Problem with creating Extra Field Groups

TableK2ExtraFieldsGroup::store failed - Table 'zupa.jos_k2_extra_fields_groups' doesn't exist SQL=INSERT INTO `jos_k2_extra_fields_groups` ( `id`,`name` ) VALUES ( '','Blog' )




Problem when I create Categorie:

PHP Fatal error: Call to undefined function mb_internal_encoding() in C:\Domains\es-s.hr\wwwroot\zupa-bili-brig\administrator\components\com_k2\tables\k2category.php on line 49



I will work site in subdomain