MATLAB: GUI panels are not showing

Question

I am working on a GUI using matlab r2015b version with multiple panels on it. What im trying to do is only show the panel that is selected on the popup menu (shown on the last picture). However, when i tried to run it, only one panel is showing even though i selected other option. No errors such as reference to non-existent field exist. It only works on the Newtons second law and Newton law of cooling, but on the other two panels, it wont work. Is it a glitch? should i upgrade to 2018 version? or am i missing a small detail? Thanks 🙂

contents = cellstr(get(hObject,'String'));
  popupmenu1 = contents(get(hObject,'value'));
  
  if strcmp (popupmenu1,'Newtons Second Law of Motion')
  set(handles.second, 'Visible', 'on');
  set(handles.mixture, 'Visible', 'off');
  set(handles.logistic, 'Visible', 'off');
  set(handles.cooling, 'Visible', 'off');
  
  elseif strcmp (popupmenu1,'Mixture Problem')
  set(handles.second, 'Visible', 'off');
  set(handles.mixture, 'Visible', 'on');
  set(handles.logistic, 'Visible', 'off');
  set(handles.cooling, 'Visible', 'off');
  
  elseif strcmp (popupmenu1,'Logistic Growth')
  set(handles.second, 'Visible', 'off');
  set(handles.mixture, 'Visible', 'off');
  set(handles.logistic, 'Visible', 'on');
  set(handles.cooling, 'Visible', 'off');
  
  elseif strcmp (popupmenu1,'Newtons Law of Cooling')
  set(handles.second, 'Visible', 'off');
  set(handles.mixture, 'Visible', 'off');
  set(handles.logistic, 'Visible', 'off');
  set(handles.cooling, 'Visible', 'on');
  
  end

Answer 1

Your code logic looks good. The issue, I think, is that you are indexing incorrectly into contents to assign a value to popupmenu1. Your code is

contents(get(hObject,'Value'))

but the code Guide provides in the callback hint is

contents{get(hObject,'Value')}

Note the use of curly braces {}