Hello, I have Odoo 8. I want to show a field only if the value of another field is XYZ. My xml definition is:

<field name="fecha" attrs="{'invisible':[('nombre_cliente', '!=', 'XYZ')]}" />

In this case, the field is invisible if the 'nombre_cliente' is XYZ or if it is another value.

If I put: <field name="fecha" attrs="{'invisible':[('nombre_cliente', '=', 'XYZ')]}" /> it works fine because if the name is XYZ the field is invisible and in another cases the field is visible.

What is my mistake? Thanks!