diff --git a/product/ERP5/Document/PackingList.py b/product/ERP5/Document/PackingList.py
index 2927e411bb360233e1145af628e73edd827e94e0..6f5cebb4526564dc3f9e10eac259c84d1688d3e2 100644
--- a/product/ERP5/Document/PackingList.py
+++ b/product/ERP5/Document/PackingList.py
@@ -112,8 +112,8 @@ class PackingList(Delivery):
           'has_cell_content': 0,
         }
         container_mvt_list = self.portal_catalog(**query_kw)
-        packed_quantity = sum([x.quantity for x in container_mvt_list \
-                               if x.quantity is not None])
+        packed_quantity = sum([x.getQuantity() for x in container_mvt_list \
+                               if x.getQuantity() is not None])
 
         if quantity != packed_quantity:
           return 0