Trying to add date to cms pages, I still have some issues

[bostamaster]

Hello everyone  
 
I want to know how to add date to CMS pages please.
 
I added a date column in the table cms_lang (default value: null)
 
I alsoadded date in CMS.php (in classes)
 
I added this line in the definition array:

date' =>             array('type' => self::TYPE_DATE, 'validate' => 'isDateFormat'),
 i also tried  
date' =>             array('type' => self::TYPE_DATE, 'validate' => 'isDateFormat'),

and created the variable public $date;
 
In adminCMScontroller.php I added this code

array(
                    'type' => 'date',
                    'label' => $this->l('Date de publication:'),
                    'name' => 'date',
                    'size' => 20,
                    'maxlength' => 10,
                    'required' => false,
                    'desc' => $this->l('Format: 2011-12-31 ')
                ),

 
 
I am using prestashop version 1.5.6.1  and I have this error when i try inserting date in the BO (when date is required) if it is not required no date is inserted. I can choose a date but when i click save  I go the error:
 

$message = $this->validateField($field, $value, $id_lang);
874. if ($message !== true)
875. {
876. if ($die)
877. throw new PrestaShopException($message);
878. return $error_return ? $message : false;
879. }
880. }
881. }

Edited April 25, 2014 by bostamaster (see edit history)