Surface tool not selecting surface

in New Users
The surface tool does not select anything in the viewport. I used it to select lights sources; I can't, now. Same thing for the universal tool. Well, it has an effect: if I select something in the scene panel and I click on the viewport, there is no more selection in the scene paneL
The surface tool is activated.
Comments
Are you sure the items have not been made unselectable: look in the Scene pane, next to the eye icon, which controls visibility, there is a pointer icon if it has a tick the item is selectable, if a cross then not.
You're right, Richard :) ! Thanks a lot !