Remember you have to reload the server when you make changes to .py files and upgrade when you make changes to the xml files for new changes to take effect

Many thanks to you, that looks right :D I will check it tomorrow when I'm at work. Maybe it's the xml file, I forgot them. I will post tomorrow if it works or not.

this is a very wrong move because if you mess up a base module the application may not open properly anymore. would advise to build a module with inherited invoice view and add you field there. You have to understand that there is an on_change function on the address in the python code and you need to add the shipping address to be affected by this function. Thus, the on_change function of address in invoice module should also change the shipping address which will also affect the view. This is why it is better to create a module of your own to incorporate all this

I know it's not good to edit base modules. How I already wrote, only for testing. The openERP is installed on a developmentserver, so if it crashes, who cares ;). For me, it's important to know, what is wrong with the code above. When I get it to work, then we do it the "clean way". But thanks for your answer.

Ok then. Firstly, I believe you need to make changes to the _view.xml file to make your field visible in a module on webclient. The xml file manages the view. If your field is not declared in the xml then you will not see it eg <field name="name" position="after"> <field name="partner_shipping_id"/></field> or something like that need to be somewhere in the xml form view. That determine where the field is displayed since you said you cannot see your field