Never give up!
I installed Visual Studio and found out that Visual Web Developer Express was not the problem. After trying all kind of options I found the solution. I use multiple .js files to structure my work and did not add Ext.Direct.addProvider(Ext.app.USER_API); in the first loaded file but in my last loaded (main) .js file. So, now I can use your group router code.
Next problem. When I submit a form, how can I use the funtions / options: isValid, waitTitle, waitMsg, success, and failure?
This is my old way of working... and is not working anymore / yet:
EDIT: have it working! Gonna love ExtJS!
r = Ext.util.JSON.decode(action.response.responseText);