Perform Validation On An Array

Im trying to perform an validation on an array but not getting the desired results. Here is my modal.

<?php

/**
 * This is the model class for table "userGameNumber".
 *
 * The followings are the available columns in table 'userGameNumber':
 * @property integer $id
 * @property integer $userId
 * @property integer $gameId
 * @property string $number
 * @property integer $megaball
 */
class UserGameNumber extends CActiveRecord
{
	/**
	 * Returns the static model of the specified AR class.
	 * @param string $className active record class name.
	 * @return UserGameNumber the static model class
	 */
	public static function model($className=__CLASS__)
	{
		return parent::model($className);
	}
	
	/**
	 * @return string the associated database table name
	 */
	public function tableName()
	{
		return 'userGameNumber';
	}

	/**
	 * @return array validation rules for model attributes.
	 */
	public function rules()
	{
		// NOTE: you should only define rules for those attributes that
		// will receive user inputs.
		return array(
			array('number, megaball', 'required'),
                        
                          array('number', 'numberCount'),
			array('userId, gameId, megaball', 'numerical', 'integerOnly'=>true),
			array('', 'length', 'max'=>255),
			// The following rule is used by search().
			// Please remove those attributes that should not be searched.
			array('id, userId, gameId, number, megaball', 'safe', 'on'=>'search'),
		);
	}

	/**
	 * @return array relational rules.
	 */
	public function relations()
	{
		// NOTE: you may need to adjust the relation name and the related
		// class name for the relations automatically generated below.
		return array(
                    'player'=>array(self::BELONGS_TO, 'User', 'userId'),
		);
	}

	/**
	 * @return array customized attribute labels (name=>label)
	 */
	public function attributeLabels()
	{
		return array(
			'id' => 'ID',
			'userId' => 'User',
			'gameId' => 'Game',
			'number' => 'Number',
			'megaball' => 'Megaball',
		);
	}

	/**
	 * Retrieves a list of models based on the current search/filter conditions.
	 * @return CActiveDataProvider the data provider that can return the models based on the search/filter conditions.
	 */
	public function search()
	{
		// Warning: Please modify the following code to remove attributes that
		// should not be searched.

		$criteria=new CDbCriteria;

		$criteria->compare('id',$this->id);
		$criteria->compare('userId',$this->userId);
		$criteria->compare('gameId',$this->gameId);
		$criteria->compare('number',$this->number,true);
		$criteria->compare('megaball',$this->megaball);

		return new CActiveDataProvider($this, array(
			'criteria'=>$criteria,
		));
	}
        //serialize the data before save to database
        public function beforeSave()
        {
            $this->number= serialize($this->number);
            return parent::beforeSave();
        }
        //transform the serialized data back into its normal form after find
        public function afterFind()
        {
            $this->number= unserialize($this->number);
            return parent::afterFind();
        }
        public function numberCount($attribute)
        {
            if (count($attribute) != 5)
            {
                $this->addError($attribute, 'you did not select enough numbers!');
            }
              
            
        }
}

i want the numberCount function to validate if there are 5 array elements in my number attribute if not generate an error. Looks like its serialized before its validated. What can i do?