diff --git a/Export/Aggregator/ActivityReasonAggregator.php b/Export/Aggregator/ActivityReasonAggregator.php
index b33c321ee..33eb0499e 100644
--- a/Export/Aggregator/ActivityReasonAggregator.php
+++ b/Export/Aggregator/ActivityReasonAggregator.php
@@ -27,13 +27,16 @@ use Chill\ActivityBundle\Security\Authorization\ActivityStatsVoter;
 use Doctrine\ORM\EntityRepository;
 use Chill\MainBundle\Templating\TranslatableStringHelper;
 use Doctrine\ORM\Query\Expr\Join;
+use Chill\MainBundle\Export\ExportElementValidatedInterface;
+use Symfony\Component\Validator\Context\ExecutionContextInterface;
 
 /**
  * 
  *
  * @author Julien Fastré <julien.fastre@champs-libres.coop>
  */
-class ActivityReasonAggregator implements AggregatorInterface
+class ActivityReasonAggregator implements AggregatorInterface,
+    ExportElementValidatedInterface
 {
     /**
      *
@@ -150,8 +153,16 @@ class ActivityReasonAggregator implements AggregatorInterface
             'label' => 'Reason\'s level'
         ));
     }
+    
+    public function validateForm($data, ExecutionContextInterface $context)
+    {
+        if ($data['level'] === null) {
+            $context->buildViolation("The reasons's level should not be empty")
+                ->addViolation();
+        }
+    }
 
-    public function getTitle()
+        public function getTitle()
     {
         return "Aggregate by activity reason";
     }
diff --git a/Resources/translations/validators.fr.yml b/Resources/translations/validators.fr.yml
new file mode 100644
index 000000000..831969641
--- /dev/null
+++ b/Resources/translations/validators.fr.yml
@@ -0,0 +1 @@
+The reasons's level should not be empty: Le niveau du sujet ne peut pas être vide