I'm working with SharePoint modal dialogs but I have some problem making the call work. When I call the OpenPopUpPage (or OpenPopUpPageWithTitle) methods I'm getting the following errors
Cannot read property 'defaultDialogWidth' of undefined
SP.Res is undefined
It would seem that part of the scripts are failing loading or missing. What are the scripts that I should load to show dialog (except sp.ui.dialog.js)?