diff --git a/library/MIDAS/models/MIDASDatabasePdo.php b/library/MIDAS/models/MIDASDatabasePdo.php
index e6f5e039c..812203bfd 100644
--- a/library/MIDAS/models/MIDASDatabasePdo.php
+++ b/library/MIDAS/models/MIDASDatabasePdo.php
@@ -320,7 +320,7 @@ public function delete($dao)
       {
       throw new Zend_Exception("The dao should be saved first ...");
       }
-    if(!isset($this->_key))
+    if(!isset($this->_key) || !$this->_key)
       {
       $query=array();
       foreach ($this->_mainData as $name => $option)