I Can't make the UI button work in any way!

I can't make the canvas and any of his features work in runtime. To be more specific and clear about whats hapen. I decide to create a working Main Menu and Pause Menu, so i started to read the documentation about that feature of unity. After that i create the first layer of the main menu, and i hit play. Everything work fin that moment, then i start to create the second layer and scripting everything. After that i can't make the canvas work in any of his features.

The ui buttons notworkin, sliders same. So i decide to take the bull by the horns, as we say in spanish. And i create a new proyect without any asset in it, and i create a simple button from the create GameObject menu. It work properly in detect "OnMauseOver", "OnClick" and so on. But then i stop the scene and ReStart it, and there is the problem again. This is frustrating.

I have Unity 5.1.4f1(32bit) personal version, i can't upgrade it for now becouse i still have my computer with Win Xp, may be is somthing about the version i dont know. Is not the way i create the ui, becouse even when i create from GameObject Menu, give me this trouble.