Problem with changing visibility of pop-up list

The code below is a part of my program. In GUI, there are 4 pop-up lists and the code is used to change their visibility. The first one is always visible. First if sets the next 3 lists invisible, the second sets only last 2 invisible, third one sets last one invisible and fourth one sets all visible.

if strcmp(handles.ws,'Jedna')
    set(handles.wsyg2, 'visible', 'off'); %line 392
    set(handles.wsyg3, 'visible', 'off');
    set(handles.wsyg4, 'visible', 'off');
    
    % Update handles structure
    guidata(hObject, handles);
    
    elseif strcmp(handles.ws,'Dwie')
    set(handles.wsyg2, 'visible', 'on');   
    set(handles.wsyg3, 'visible', 'off');  
    set(handles.wsyg4, 'visible', 'off');  
    
    % Update handles structure
    guidata(hObject, handles);
    
    elseif strcmp(handles.ws,'Trzy')
    set(handles.wsyg2, 'visible', 'on');
    set(handles.wsyg3, 'visible', 'on');
    set(handles.wsyg4, 'visible', 'off');
    
    % Update handles structure
    guidata(hObject, handles);
    
    elseif strcmp(handles.ws,'Cztery')
    set(handles.wsyg2, 'visible', 'on');
    set(handles.wsyg3, 'visible', 'on');
    set(handles.wsyg4, 'visible', 'on');
    
    % Update handles structure
    guidata(hObject, handles);
end

The problem is that after, for example, setting all 4 lists visible and choosing values from them, it is impossible to go back: I can't choose to have only one visible. I get this error:

Error using set
Invalid handle

Error in SOI_projekt>ws_Callback (line 392)
set(handles.wsyg2, 'visible', 'off');

Error in gui_mainfcn (line 95)
        feval(varargin{:});

Error in SOI_projekt (line 43)
    gui_mainfcn(gui_State, varargin{:});

Error in matlab.graphics.internal.figfile.FigFile/read>@(hObject,eventdata)SOI_projekt('ws_Callback',hObject,eventdata,guidata(hObject))
 
Error while evaluating UIControl Callback.

Thanks for help.

Answer 1

[Jan]

What is the purpose of:

    % Update handles structure
    guidata(hObject, handles);    

For some unknown reasons the value of handles.wsyg2 has been overwritten or the corresponding object was deleted or replaced. Check this using the debugger:

    dbstop if error    

Then run the code again until it stops at the error. Now check the value of handles.wsyg2 .

If the corresponding object was deleted, this did not happen in the shown part of the code, but somewhere else.

[Adrian Luzniak]

You're right, handles.wsyg2 does not work properly - same goes for 3 and 4.

But, what is the best way to check value of handles.wsyg2? Get function does not work, at least I can't get it to work.