diff --git a/prospect.py b/prospect.py
index 14070be..ea777f0 100644
--- a/prospect.py
+++ b/prospect.py
@@ -38,36 +38,6 @@ class Prospect(ModelSQL, ModelView):
 
     prospect_trace = fields.Many2One('sale.prospect_trace', 'Prospect trace')
 
-    @classmethod
-    def __setup__(cls):
-        super(Prospect, cls).__setup__()
-        cls._buttons.update({
-            'start_trace': {
-                'invisible': Eval('state') == 'unassigned'
-            }
-        })
-
-    @classmethod
-    @ModelView.button
-    def start_trace(cls, prospects):
-        pool = Pool()
-        ProspectTrace = pool.get('sale.prospect_trace')
-        for prospect in prospects:
-            if prospect.prospect_trace:
-                return
-
-            prospect_trace = ProspectTrace(
-                prospect=prospect,
-                prospect_city=prospect.city,
-                prospect_business_unit=prospect.business_unit,
-                prospect_assigned_operator=prospect.assigned_operator,
-                prospect_contacts=prospect.contact_methods
-            )
-            prospect_trace.save()
-
-            prospect.prospect_trace = prospect_trace
-            prospect.save()
-
     @classmethod
     def default_state(cls):
         return 'unassigned'
@@ -161,11 +131,26 @@ class AssignOperator(Wizard):
     assign = StateTransition()
 
     def transition_assign(self):
+        pool = Pool()
+        ProspectTrace = pool.get('sale.prospect_trace')
+
         for prospect in self.start.prospects:
             prospect.assigned_operator = self.start.operator
             prospect.state = 'assigned'
             prospect.save()
 
+            prospect_trace = ProspectTrace(
+                prospect=prospect,
+                prospect_city=prospect.city,
+                prospect_business_unit=prospect.business_unit,
+                prospect_assigned_operator=prospect.assigned_operator,
+                prospect_contacts=prospect.contact_methods
+            )
+            prospect_trace.save()
+
+            prospect.prospect_trace = prospect_trace
+            prospect.save()
+
         return 'end'
 
 
diff --git a/tests/scenario_sale_opportunity_management.rst b/tests/scenario_sale_opportunity_management.rst
index 7451845..da358ad 100644
--- a/tests/scenario_sale_opportunity_management.rst
+++ b/tests/scenario_sale_opportunity_management.rst
@@ -177,9 +177,8 @@ Seguimiento de prospecto 2
     * Seguimiento de prospecto al que pertence
 
 
-Crear seguimiento de prospecto::
+Verificar creación de seguimiento de prospecto::
     >>> ProspectTrace = Model.get('sale.prospect_trace')
-    >>> prospect1.click('start_trace')
     >>> prospect_trace, = ProspectTrace.find([('prospect', '=', prospect1)])
 
     >>> prospect_trace.prospect.name
@@ -280,6 +279,7 @@ Reasignar prospectos por operador::
     >>> reassign_by_operator.form.new_operator = operator2
     >>> reassign_by_operator.execute('reassign_by_operator')
 
+    >>> prospect1.reload()
     >>> prospect1.assigned_operator.name
     'Operatus'
 
diff --git a/view/prospect_tree.xml b/view/prospect_tree.xml
index bd36f14..b868fc9 100644
--- a/view/prospect_tree.xml
+++ b/view/prospect_tree.xml
@@ -7,5 +7,4 @@ this repository contains the full copyright notices and license terms. -->
     <field name="department" expand="1"/>
     <field name="city" expand="1"/>
     <field name="assigned_operator" expand="1"/>
-    <button name="start_trace"/>
 </tree>
\ No newline at end of file