Listview checkbox

[Razor]

I want to get checked items with code(programaticly) when i use the code bellow its shows an error.

Delphi-Quellcode:

procedure TForm1.Button5Click(Sender: TObject);
begin

if listview1.Items.Item[listview1.VisibleItems].Checked=true  then
 form1.caption:='some items have been checked';


    end;
end.