( ! ) Fatal error: method_exists() [function.method-exists]

Hello, I have this question.

I’m using CAdvancedArBehavior to achieve some improvements on a model (Alumno).

And I want to export a list ( filtered and sorted ) to excel.
So I followed a tutorial and I added this on search method:

//Para reporte y exportacion
	$_SESSION['alumno_datos_filtro'] = new CActiveDataProvider($this, array(
		'criteria' => $criteria, 
		'sort' => $sort,			
		'pagination' => false,

But when I try to get data from that Data Provider i get a FatalError…

When I look in var_dump, I found this:

      private '_m' => 
      'CAdvancedArBehavior' => 

Why ? the class is incomplete?

I configured CAdvancedArBehavior like this:
in main.php


and in the model: Alumno

        public function behaviors(){
            return array( 'CAdvancedArBehavior' => array(
                    'class' => 'application.extensions.CAdvancedArBehavior')); 

May be the class is not loaded completely ?
How to verify that?

Notice that the error has one letter in tehe name of the class NOT capitalized:

( ! ) Fatal error: method_exists() [function.method-exists]: The script tried to execute a method or access a property of an incomplete object. Please ensure that the class definition “CAdvancedArbehavior” of the object you are trying to operate on was loaded before unserialize() gets called or provide a __autoload() function to load the class definition in C:\xampp\htdocs\yii-1.1.12\framework\base\CComponent.php on line 558

So I changed all the places in my source… but the problem stay.

Any idea ?

Best Regards