Form Validation Message Not showing

[Nishanthan93]

i am developing module for CRUD operations . created form using fields_form . all the functionality are working correctly and the validation also working correclty But the validation error message was not displayed . i am created a admin controller in my module .
AdminController
 

 public function __construct()

    {
        parent::__construct();

        $this->bootstrap = true;

        $this->table = 'econt_shipping_cost'; 

        $this->identifier = 'id'; 

        $this->className = 'EcontShipping'; 

        $this->allow_export = true; 

        $this->_defaultOrderBy = 'a.id'; 

        $this->fields_list = [
            'id' => ['title' => 'ID','class' => 'fixed-width-xs'],
            'weight_from' => ['title' => 'Weight From'],
            'weight_to' => ['title' => 'Weight To'],
            'econt_office' => ['title' => 'To Office Cost'],
            'econt_door' => ['title' => 'To Door Cost'],
        ];

        $this->addRowAction('edit');

        $this->addRowAction('delete');

        $this->fields_form = [
        'legend' => [
            'title' => 'Shipping Cost',
            'icon' => 'icon-list-ul'
        ],
        'input' => [
            ['name'=>'weight_from','type'=>'text','label'=>'Weight From','required'=>true,],
            ['name'=>'weight_to','type'=>'text','label'=>'Weight To','required'=>true],
            ['name'=>'econt_office','type'=>'text','label'=>'To Office Cost','required'=>true],
            ['name'=>'econt_door','type'=>'text','label'=>'To Door Cost','required'=>true],
        ],
        'submit' => [
            'title' => $this->trans('Save', [], 'Admin.Actions'),
        ]
        ];

        
    }

 

myclass

class EcontShipping extends ObjectModel {

  public $id;
  public $weight_from;
  public $weight_to;
  public $econt_office;
  public $econt_door;

  public static $definition = [
    'table' => 'econt_shipping_cost',
    'primary' => 'id',
    'displayError' => 'true',
    'fields' => [
      'weight_from' =>  ['type' => self::TYPE_FLOAT, 'validate' => 'isFloat', 'required'=>true],
      'weight_to' =>  ['type' => self::TYPE_FLOAT, 'validate' => 'isFloat', 'required'=>true],
      'econt_office' =>  ['type' => self::TYPE_FLOAT, 'validate' => 'isFloat', 'required'=>true],
      'econt_door' =>  ['type' => self::TYPE_FLOAT, 'validate' => 'isFloat', 'required'=>true],
    ],
  ];
}