diff --git a/src/Message/NotificationRequest.php b/src/Message/NotificationRequest.php
index 2270ca3..82121e9 100644
--- a/src/Message/NotificationRequest.php
+++ b/src/Message/NotificationRequest.php
@@ -90,13 +90,13 @@ private function getSignature()
     private function buildSignature()
     {
         $params = [
-            $this->getNotificationType(),
-            $this->getOperationId(),
-            $this->getAmount(),
-            $this->getCurrency(),
-            $this->getDatetime(),
-            $this->getSender(),
-            $this->getCodePro(),
+            $this->getDataItem('notification_type'),
+            $this->getDataItem('operation_id'),
+            $this->getDataItem('amount'),
+            $this->getDataItem('currency'),
+            $this->getDataItem('datetime'),
+            $this->getDataItem('sender'),
+            $this->getDataItem('codepro'),
             $this->getSecret(),
             $this->getDataItem('label', ''),
         ];