The error message issue has being resolved but I am stuck still. The sale order object indeed does not have the tax_id but the form view does. Check out the file at ../openerp/server/addons/sale/sale_view.xml To further test what you said about why it should not work, I changed my targeted field to client_order_ref, which is a field that belongs to the sale order object. See my xml file content at https://gist.github.com/drupalista-br/4bf8facff175c1800908 The custom xml file is producing no changes on the targed form view whatsoever. I have taken the following precautions: * Restarted the server * Updated my custom module at Settings -> Installed Modules * Tested the xpath path parameter. It does point to the targeted field.

The view has the field tax_id, but it belongs to sale order line. You may take a route to that field using complete xpath(form/notebook/page/field/form/group) and I am sure it will work.

My issue did not lie on the xml syntax but for not declaring a dependency to the sale and stock modules in the manifest file.

Alright, mentioning the dependency is first. Close the question if its resolved. Thanks.

Why would I close the question? It might help someone else.

Meant, Close as solved by choosing an answer!