diff --git a/webapp/services/callback/OutAppPurchase.php b/webapp/services/callback/OutAppPurchase.php
index 1eec1078..f9d599af 100644
--- a/webapp/services/callback/OutAppPurchase.php
+++ b/webapp/services/callback/OutAppPurchase.php
@@ -103,7 +103,7 @@ class OutAppPurchase {
 
     private function verifySign()
     {
-
+        $params = array_merge($_REQUEST, array());
     }
 
 }