data not coming after using parent join

I have used http://www.yiiframework.com/wiki/621/filter-sort-by-calculated-related-fields-in-gridview-yii-2-0/ tutorial and its great for any.

all working fine but I get stuck after adding "Scenario 3 Steps"

// filter by parent name

$query->joinWith(['parent' => function ($q) {


    $q->where('parent.first_name LIKE "%' . $this->parentName . '%" ' .


    'OR parent.last_name LIKE "%' . $this->parentName . '%"');


}]);

it fires mysql query like:

SELECT COUNT(*) FROM person LEFT JOIN country ON person.country_id = country.id LEFT JOIN person parent ON person.id = parent.parent_id WHERE parent.first_name LIKE "%%" OR parent.last_name LIKE "%%"

which doesnt returns any records.

so how to fix it?