Yii2 - DynamicModel validator attribute when not working - php

Question

I am trying to use Yii2's conditional validator within DynamicModel clas, but the validator when is not working:
Controller
private function createFormModel(){
$model = new DynamicModel([
'indicador',
'departamento',
'mes'
]);
$model->addRule(['indicador'],'required',['message' => 'Este campo es obligatorio']);
$model->addRule(['departamento'], 'required', ['when' => function ($model) {
return $model->indicador == 'Semana';
}]);
return $model;
}
public function actionCuatrimestre()
{
$model = $this->createFormModel();
return $this->render('cuatrimestre',[
'model' => $model,
]);
}
Whether I select or not the "indicador" field which is a select field, the "departamento" field alwasys returns as required. I have algo try this way but with no results:
$model->addRule(['departamento'], 'required', ['when' => function ($model) {
return $model->indicador == 'Semana';
}], ['whenClient' => "function (attribute, value) {
return $('#indicador').val() == 'Semana';
}"]);
What I am missing here?
EDIT
My view code cuatrimestre.php
<?php $form = ActiveForm::begin(); ?>
<div class="form-group">
<?= $form->field($model, 'indicador')->widget(Select2::class, [
'options' => ['id'=>'indicador'],
'data' => ['Semana','Día','Resumen'],
]); ?>
</div>
<div class="form-group">
<?= $form->field($model, 'departamento')->widget(Select2::class, [
'options' => ['id'=>'departamento'],
'data' => Departamentos::getDepartamentosByUser(),
]); ?>
</div>
<div class="form-group">
<?= $form->field($model, 'curso')->widget(DepDrop::class, [
'type' => DepDrop::TYPE_SELECT2,
'options' => ['id' => 'curso-id'],
'select2Options' => ['pluginOptions' => ['allowClear' => true]],
'pluginOptions' => [
'depends' => ['departamento-id'],
'placeholder'=>'Seleccionar curso',
'url' => Url::to(['/campus-actividad/subcursos']),
'loadingText' => 'Cargando ...',
'initialize' => true,
]
]);?>
</div>
<div>
<?= Html::submitButton('Aplicar filtros', ['class' => 'btn btn-block btn-default']) ?>
<?php ActiveForm::end(); ?>
</div>