i followed the guideHERE
But i can’t understand what i did wrong 
, maybe i missed something … all the search in CGridView gave me blank results .
Model
class Tesi extends CActiveRecord {
public $docente_search;
public $materia_search;
---RULES
array('id, title, title_eng, tesifile, absfile, abstract, users_search, docente_search, materia_search, publication_date, commenti, totaledeitotali,votazione, acc_pubblicazione, tags, status, matricola, tblusersid, privacy', 'safe', 'on' => 'search'),
public function relations() {
// NOTE: you may need to adjust the relation name and the related
// class name for the relations automatically generated below.
Yii::import('application.modules.user.models.*');
return array(
'tags' => array(self::HAS_MANY, 'Tag', 'tag'),
'corsi' => array(self::BELONGS_TO, 'Corsi', 'corsi_id'),
'docente' => array(self::BELONGS_TO, 'Docente', 'docente_id'),
'facolta' => array(self::BELONGS_TO, 'Facolta', 'facolta_id'),
'materia' => array(self::BELONGS_TO, 'Materia', 'materia_id'),
'users' => array(self::BELONGS_TO, 'User', 'tblusersid'),
);
public function search() {
// @todo Please modify the following code to remove attributes that should not be searched.
$criteria = new CDbCriteria;
$criteria->with = array( 'docente' );
$criteria->compare( 'docente.surname', $this->docente_search, true );
$criteria->compare('id', $this->id, true);
$criteria->compare('title', $this->title, true);
$criteria->compare('title_eng', $this->title_eng, true);
$criteria->compare('abstract', $this->abstract, true);
$criteria->compare('publication_date', $this->publication_date, true);
$criteria->compare('privacy', $this->privacy);
$criteria->compare('users', $this->user_search, true);
$criteria->with = array( 'users');
$criteria->compare('materia_id', $this->materia_search, true);
$criteria->with = array( 'materia');
$criteria->scopes='pubblicate';
return new CActiveDataProvider($this, array(
'criteria' => $criteria,
'sort'=>array(
'attributes'=>array(
'facolta_search'=>array(
'asc'=>'facolta.name',
'desc'=>'facolta.name DESC',
),
),
), ));
}
in view
array(
'name'=>'materia',
'value'=>'$data->materia->name',
'filter' => CHtml::activeTextField($model, 'materia_search'),
),
array(
'name'=>'docente',
'value'=>'$data->docente->fullName()',
'filter'=>CHtml::activeTextField($model, 'materia_search'),
),
'tags',
//array(
// 'class'=>'CButtonColumn',
//),
),
)); ?>
What i missed ?? 
thanks a lot for your help