diff --git a/product/ERP5/Document/Inventory.py b/product/ERP5/Document/Inventory.py
index 7fa6f0da4e5b5821f6cf0a1ab452b238c110a2da..ccc843a35a9b2ccba9018cb55e1ecfa05eb33c8e 100755
--- a/product/ERP5/Document/Inventory.py
+++ b/product/ERP5/Document/Inventory.py
@@ -81,7 +81,7 @@ class Inventory(Delivery):
       node = self.getDestination()
       for movement in self.getMovementList():
         resource =  movement.getResourceValue()
-        if resource is not None:
+        if resource is not None and movement.getInventory() is not None:
           variation_text = movement.getVariationText()
           if (resource,variation_text) not in resource_and_variation_list:
             resource_and_variation_list.append((resource,variation_text))