Not yet set when validating.

src/engine/gameManager/ForgeManager.java

@@ -137,7 +137,7 @@ public enum ForgeManager implements Runnable {
 
         // Forge must be protected in order to access warehouse.
 
-        if (workOrder.production_cost_total.size() > 1)
+        if (calcProductionCost(workOrder).size() > 1)
             if (!workOrder.vendor.building.protectionState.equals(mbEnums.ProtectionState.PROTECTED)) {
                 if (playerCharacter != null)
                     ErrorPopupMsg.sendErrorPopup(playerCharacter, 193);     //193: Production denied: This building must be protected to gain access to warehouse