diff --git a/models/sale.py b/models/sale.py
index ee54afb395cc6ea1dfef8f33041b1777d371d84a..5f8ed9a979c18084c598e0c361854d9e609c1d87 100644
--- a/models/sale.py
+++ b/models/sale.py
@@ -63,15 +63,6 @@ class FinacoopSaleOrder(models.Model):
         if self.lettre_coop:
             self.content_html = self.lettre_coop.body_html
 
-    @api.multi
-    def action_confirm(self):
-        if self.lettre_coop_sale:
-            if not self.pdf_lettre_signe:
-                return False
-        res = super(FinacoopSaleOrder, self).action_confirm()
-        return True
-
-
     @api.multi
     def validate_lc(self):
         self.filtered(lambda s: s.state == 'draft').write({'state': 'lc_ok'})
diff --git a/views/sale_views.xml b/views/sale_views.xml
index cebae38d98dfb0c88122049cf10a42fbda0ea5e5..bb8e04d767e12656d5a3416ee841d0269735dcbf 100644
--- a/views/sale_views.xml
+++ b/views/sale_views.xml
@@ -9,7 +9,10 @@
             <field name="arch" type="xml">
                 <!-- HEADER FORM -->
                 <xpath expr="//button[@name='action_cancel']" position="after">
-                    <button name="%(finacoop_wizard_lettre_preview)d" string="Prévisualiser lettre de Coop" type="action" attrs="{'invisible': [('state', '!=', 'draft')]}" />
+                    <button name="%(finacoop_wizard_lettre_preview)d"
+                            string="Prévisualiser lettre de Coop"
+                            type="action"
+                            attrs="{'invisible': ['|', ('state', '!=', 'draft'), ('lettre_coop', '=', False)]}" />
                 </xpath>
                 <!-- Senb by email -->
                 <xpath expr="//button[@name='action_quotation_send']" position="attributes">
@@ -21,14 +24,24 @@
                     <attribute name="class"></attribute>
                 </xpath>
                 <xpath expr="//button[@name='print_quotation']" position="before">
-                    <button name="validate_lc" string="Valider LC" type="object" states="draft" class="btn-primary"/>
+                    <button name="validate_lc"
+                            string="Valider LC"
+                            type="object"
+                            attrs="{'invisible': ['|', ('state', '!=', 'draft'), ('lettre_coop', '=', False)]}"
+                            class="btn-primary"/>
                 </xpath>
                 <xpath expr="//button[@name='action_confirm'][2]" position="attributes">
                     <attribute name="states">lc_ok</attribute>
                 </xpath>
                 <!-- Print LC -->
                 <xpath expr="//button[@name='print_quotation'][2]" position="before">
-                    <button name="%(report_finacoop_lettre_coop_pdf)d" string="Imprimer LC" icon="fa-print" type="action" states="lc_ok,sent,sale" class="btn-primary"/>
+                    <button
+                            name="%(report_finacoop_lettre_coop_pdf)d"
+                            string="Imprimer LC"
+                            icon="fa-print"
+                            type="action"
+                            attrs="{'invisible': ['|', ('state', 'not in', ('lc_ok', 'sent', 'sale')), ('lettre_coop', '=', False)]}"
+                            class="btn-primary"/>
                 </xpath>
                 <!-- Cancel -->
                 <xpath expr="//button[@name='action_cancel']" position="attributes">
@@ -47,12 +60,12 @@
                     <field name="contact" attrs="{'invisible': [('partner_id', '=', False)]}" domain="[('parent_id', '=', partner_id)]" />
                 </xpath>
                 <xpath expr="//field[@name='payment_term_id']" position="after">
-                    <field name="lettre_coop" required="1" />
-                    <field name="millesime" required="1" />
+                    <field name="lettre_coop" />
+                    <field name="millesime" attrs="{'required': [('lettre_coop', '!=', False)]}"/>
                     <field name="tarifs_horaires"  attrs="{'readonly': [('state', '!=', 'draft')]}"/>
                 </xpath>
                 <xpath expr="//notebook" position="before">
-                    <div>
+                    <div attrs="{'invisible': ['|', ('state', '!=', 'draft'), ('lettre_coop', '=', False)]}">
                         <label for="pdf_lettre_signe"/>: <field name="pdf_filename" invisible="1"/><field widget="binary" name="pdf_lettre_signe" filename="pdf_filename"/>
                     </div>
                 </xpath>
@@ -83,7 +96,7 @@
                             </group>
                         </group>
                     </page>
-                    <page string="Lettre de Coop" name="lc_preview">
+                    <page string="Lettre de Coop" name="lc_preview" attrs="{'invisible': [('lettre_coop', '=', False)]}">
                         <group>
                             <group>
                                 <field name="annexe1"/>