Adding in missed reference

src/apicore/structure/response.php

@@ -82,7 +82,7 @@ public static function addError($code, $message){
     public function xml2array ( $xmlObject, $out = array () )
     {
         foreach ( (array) $xmlObject as $index => $node )
-            $out[$index] = ( is_object ( $node ) ||  is_array ( $node ) ) ? xml2array ( $node ) : $node;
+            $out[$index] = ( is_object ( $node ) ||  is_array ( $node ) ) ? $this->xml2array ( $node ) : $node;
 
         return $out;
     }