The custom form of the add-on without administration interface is displayed

I am trying to develop an add-on that runs in the administration space. It's very simple. I am using WP_List_Table to display a list of the elements in the database. That works perfect. I have a "Add" button on the form. When I press it the entire administration interface disappears. The only thing that shows my form. I think there is something that is simple that I am doing wrong. I can not find anything on the web to help me. Can someone give me a suggestion? May thank you in advance.