diff --git a/product/ERP5/Interaction.py b/product/ERP5/Interaction.py
index 3898e2f7c1bddf24d2dc55bcf28ff3b81f05c408..e10413e748d4a7ba857b8b1deaf0d734a4c4f89b 100644
--- a/product/ERP5/Interaction.py
+++ b/product/ERP5/Interaction.py
@@ -21,8 +21,6 @@
 $Id$
 """
 
-from string import join, split, strip
-
 from OFS.SimpleItem import SimpleItem
 from Globals import DTMLFile, PersistentMapping
 from Acquisition import aq_inner, aq_parent
@@ -37,6 +35,7 @@ from Products.DCWorkflow.Expression import Expression
 from Products.DCWorkflow.Transitions import TRIGGER_AUTOMATIC, TRIGGER_WORKFLOW_METHOD
 
 from Products.ERP5 import _dtmldir
+from Products.ERP5Type.Base import _aq_reset
 
 class InteractionDefinition (SimpleItem):
     meta_type = 'Workflow Interaction'
@@ -156,6 +155,8 @@ class InteractionDefinition (SimpleItem):
         self.actbox_name = str(actbox_name)
         self.actbox_url = str(actbox_url)
         self.actbox_category = str(actbox_category)
+        # reset _aq_dynamic method cache.
+        _aq_reset()
         if REQUEST is not None:
             return self.manage_properties(REQUEST, 'Properties changed.')