Use hooks in functoins.php of theme

I added the code

function bcze_activation(){

}
function bcze_deactivation(){

}
function bcze_install(){

}
add_action("after_setup_theme", "bcze_install");
add_action("after_switch_theme", "bcze_activation");
add_action("switch_theme", "bcze_deactivation");

to my themes functions.php and now all that happens when I open the front-end or back-end is an empty body in an html tag. I doesn’t get any content of anything and no errors at all. I hope you have an idea how to fix that.