diff --git a/addons/account_voucher/voucher_sales_purchase_view.xml b/addons/account_voucher/voucher_sales_purchase_view.xml
index 0cb3104f92e..5b3965ad59b 100644
--- a/addons/account_voucher/voucher_sales_purchase_view.xml
+++ b/addons/account_voucher/voucher_sales_purchase_view.xml
@@ -153,7 +153,7 @@
                         <button name="cancel_voucher" string="Cancel" states="draft,proforma"  icon="gtk-cancel"/>
                         <button name="cancel_voucher" string="Cancel" type="object" states="posted" icon="terp-stock_effects-object-colorize" confirm="Are you sure to confirm this record ?"/>
                         <button name="proforma_voucher" string="Validate" states="draft" icon="gtk-go-forward"/>
-                        <group attrs="{'invisible':['|', ('state','!=','posted'), ('paid','=',True)]}">
+                        <group attrs="{'invisible':['|', ('state','=','posted'), ('paid','=',True)]}">
                            <button icon="terp-dolar_ok!" name="%(act_pay_voucher)d" context="{'narration':narration, 'title':'Customer Payment', 'type':'receipt', 'partner_id':partner_id, 'reference':reference, 'amount':amount}" type="action" string="Pay" attrs="{'invisible':[('pay_now','=','pay_now')]}"/>
                         </group>
                         <button name="action_cancel_draft" type="object" states="cancel" string="Set to Draft" icon="terp-stock_effects-object-colorize"/>