diff --git a/application/models/UserInGroup.php b/application/models/UserInGroup.php
index 6fc1360a706..2ca1d43c671 100644
--- a/application/models/UserInGroup.php
+++ b/application/models/UserInGroup.php
@@ -45,8 +45,8 @@ public function tableName()
 	 */
 	public function primaryKey()
 	{
-		return 'uid';
-	}
+        return array('ugid', 'uid');
+    }
 
 	/**
      * @return array relational rules.