change position field 'equipments create'

purchase.py

@@ -70,7 +70,8 @@ class Line(metaclass=PoolMeta):
     address_equipment = fields.Many2One('party.address', "Direccion", required=True)
     serial_equipment = fields.Char("Serial", size=None, required=True)
     refurbish = fields.Boolean("Refurbish")
-    product_equipment = fields.Boolean("Product Equipment")
+    product_equipment = fields.Boolean("Product Equipment",
+                                       states={'readonly': True})
     
     @classmethod
     def default_address_equipment(cls):

view/purchase_form.xml

@@ -2,8 +2,7 @@
 <!--This file file is part of Tryton. The COPYRIGHT file at the top level of this repository contains the full copyright notices and license terms. -->
 <data>
     <xpath
-	expr="/form/notebook/page[@id='info']/separator[@name='comment']"
-	position="before">
+	expr="/form/field[@name='invoice_address']" position="after">
 	    <label name="equipment_create"/>
 	    <field name="equipment_create"/>
     </xpath>