diff --git a/modules/purchase_trade/valuation.py b/modules/purchase_trade/valuation.py
index 3ab5dda..cf18b52 100644
--- a/modules/purchase_trade/valuation.py
+++ b/modules/purchase_trade/valuation.py
@@ -284,9 +284,9 @@ class ValuationBase(ModelSQL):
         Currency = Pool().get('currency.currency')
         FeeLots = Pool().get('fee.lots')
         #if line is matched with sale_line we should add the open sale side
-        sale_lines = line.get_matched_lines()
-        sale_open_lots = [s.lot_s for s in sale_lines]
-        all_lots = (line.lots or []) + sale_open_lots
+        sale_lines = line.get_matched_lines() or []
+        sale_open_lots = tuple(s.lot_s for s in sale_lines if s.lot_s)
+        all_lots = (line.lots or ()) + sale_open_lots
         for lot in all_lots:
             fl = FeeLots.search([('lot', '=', lot.id)])
             if not fl: