@aharoen: If I am honest, I do not know what you mean with your comment... I hope you can explain me...

I only set up the community's predefined webkit replacements for the reports I need. I expected that they are completely finished replacing the old .rml ones and that I can simply edit the .maco file to customize them. That's why I did not install them inside OpenERP's general addon directory, but in my own additional addon folder already containing other custom modules made by me.

I read several documentation what I have to do to get webkit running and I followed all steps. Maybe, there is little information missing which seems to go without saying, but I do not know about. I wonder how the system can still print the old .rml report, if all connection to it was replaced by webkit replacements...

Could this simply be a module update thing? - Yesterday, I downloaded some bzr branches to my additional addon folder (yes, this is entered in openerp config, too), but although having changed rights and owner of these branches, logged off my database, restarted openerp service, logged in again, updated all modules, I was not able to see them in module management to install them. I use Ubuntu 12.04. I think, openerp has got a real problem with its module update functionality: For example, I did some test overrides for some reporting services to replace the standard .rml files. These are inside my addon folder and only installed into one special database. When changing the database (I logged off this database and into another one), the system was searching for these replacing reports, although they were not installed into this database ??? I was not able to work with this new database, before having completely removed these services from my addon folder ???

@Jaakko Komulainen: For such kinds of tests I always duplicate a preconfigured template database with no data and special modules installed so far. So I first had to set up webkit and afterwards, I created a new test invoice, pressed the print button and the old .rml report appeared.