Error registrando boton en ProspectTrace

prospect.xml

@@ -134,7 +134,6 @@ this repository contains the full copyright notices and license terms. -->
             <field name="model">sale.prospect, -1</field>
             <field name="action" ref="assign_operator_wizard"/>
         </record>
- 
         <menuitem
                 parent="menu_prospects_tree"
                 sequence="40"

prospect_trace.py

@@ -3,6 +3,7 @@
 from trytond.wizard import Wizard, StateView, Button, StateTransition
 from trytond.model import ModelSQL, ModelView, fields, DeactivableMixin
 from trytond.pool import Pool
+from trytond.pyson import Eval
 
 from .selections.call_types import CallTypes
 from .selections.interest import Interest
@@ -35,10 +36,25 @@ class ProspectTrace(DeactivableMixin, ModelSQL, ModelView):
             ], 'State',
             states=_states)
 
+    @classmethod
+    def __setup__(cls):
+        super(ProspectTrace, cls).__setup__()
+        cls._buttons.update({
+            'wizard_schedule': {
+                'invisible': Eval('state') == 'open',
+                }
+        })
+
     @classmethod
     def default_state(cls):
         return 'open'
 
+    @classmethod
+    @ModelView.button_action(
+        'sale_opportunity_management.schedule_call_wizard')
+    def wizard_schedule():
+        pass
+
     @fields.depends('calls', 'pending_call', 'current_interest', 'state')
     def on_change_calls(self):
         if not self.calls:

prospect_trace.xml

@@ -54,12 +54,19 @@ this repository contains the full copyright notices and license terms. -->
             id="menu_prospect_trace_tree"
             action="act_prospect_trace_tree"/>
 
-        <!-- <record model="ir.action.wizard" id="schedule_call_wizard"> -->
-
+        <record model="ir.action.wizard" id="schedule_call_wizard">
+            <field name="name">Schedule call</field>
+            <field name="wiz_name">sale.prospect_trace.schedule</field>
+        </record>
         <record model="ir.ui.view" id="schedule_start_view_form">
             <field name="model">sale.prospect_trace.schedule.start</field>
             <field name="type">form</field>
             <field name="name">schedule_start_form</field>
         </record>
+        <record model="ir.model.button" id="schedule_call_wizard_button">
+            <field name="name">wizard_schedule</field>
+            <field name="string">Schedule call</field>
+            <field name="model" search="[('model', '=', 'sale.prospect_trace')]"/>
+        </record>
     </data>
 </tryton>

view/schedule_start_form.xml

@@ -2,5 +2,7 @@
 <!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
 this repository contains the full copyright notices and license terms. -->
 <form>
-    
+    <label name="date_time"/>
+    <field name="date_time"/>
+    <button name="wizard_schedule" icon="tryton-forward"/>
 </form>