Private-Messaging

I follow the instructions of Private-Messaging, but I see error as follows:
"Active record "Message" has an invalid configuration for relation "receiver". It must specify the relation type, the related active record class and the foreign key."

My config/main.php:

'message' => array(
                        'userModel' => 'User',
                        'getNameMethod' => 'getFullName',
                        'getSuggestMethod' => 'getSuggest',
                        //'viewPath' => '/message/fancy',
                        
                        'receiverRelation' => array(
                                        CActiveRecord::BELONGS_TO,
                                        'User',
                                        'on' => 'User.id = receiver_id'
                        ),

                        
                                                )

                        'senderRelation' => array(
                                        CActiveRecord::BELONGS_TO,
                                        'User',
                                        'on' => 'User.id = sender_id'
                        ),

                                
        ),

This is my post, it have error "Active record "Message" has an invalid configuration for relation "receiver" "
https://www.dropbox.com/s/oq1jpbfpftih6mo/message.rar

Can someone please help me ?!