diff --git a/bt5/erp5_base/WorkflowTemplateItem/portal_workflow/delivery_movement_causality_interaction_workflow/scripts/DeliveryMovement_calculate.xml b/bt5/erp5_base/WorkflowTemplateItem/portal_workflow/delivery_movement_causality_interaction_workflow/scripts/DeliveryMovement_calculate.xml
index a814cb0f7144082ef720762cfc26b257125335d2..abcf3884546e1ef6bd4e93fe76942a07c094c8f1 100644
--- a/bt5/erp5_base/WorkflowTemplateItem/portal_workflow/delivery_movement_causality_interaction_workflow/scripts/DeliveryMovement_calculate.xml
+++ b/bt5/erp5_base/WorkflowTemplateItem/portal_workflow/delivery_movement_causality_interaction_workflow/scripts/DeliveryMovement_calculate.xml
@@ -50,7 +50,9 @@
         </item>
         <item>
             <key> <string>_body</string> </key>
-            <value> <string>state_change[\'object\'].getExplanationValue().Delivery_calculate()\n
+            <value> <string>explanation_value = state_change[\'object\'].getExplanationValue()\n
+if explanation_value:\n
+  explanation_value.Delivery_calculate()\n
 </string> </value>
         </item>
         <item>