I am really really sorry for my stupid post. I was trying the Grocery CRUD with a project which already has had a database. but i did what u said(i tried a new project with 'test_database.sql') and everything is working now! I'm going to delete the G. Crud files in my old project and start every thing again. I'm sure it will work this time, I must did sth wrong.
By the way, you did a fantastic job, thanks for this useful tool.