GUI bug for pop-up menu

I am learning GUI and I followed the online document buildgui.pdf to build the example GUI, simple_gui. However, when I run it, I found I cannot switch back to peaks after selected membrane and sinc in pop-up menu even though the peaks apprears in the beginning when I open the GUI. Here is the code:

function varargout = simple_gui(varargin) % SIMPLE_GUI MATLAB code for simple_gui.fig % SIMPLE_GUI, by itself, creates a new SIMPLE_GUI or raises the existing % singleton*. % % H = SIMPLE_GUI returns the handle to a new SIMPLE_GUI or the handle to % the existing singleton*. % % SIMPLE_GUI('CALLBACK',hObject,eventData,handles,...) calls the local % function named CALLBACK in SIMPLE_GUI.M with the given input arguments. % % SIMPLE_GUI('Property','Value',...) creates a new SIMPLE_GUI or raises the % existing singleton*. Starting from the left, property value pairs are % applied to the GUI before simple_gui_OpeningFcn gets called. An % unrecognized property name or invalid value makes property application % stop. All inputs are passed to simple_gui_OpeningFcn via varargin. % % *See GUI Options on GUIDE's Tools menu. Choose "GUI allows only one % instance to run (singleton)". % % See also: GUIDE, GUIDATA, GUIHANDLES

% Edit the above text to modify the response to help simple_gui

% Last Modified by GUIDE v2.5 25-Nov-2013 08:03:18

% Begin initialization code - DO NOT EDIT gui_Singleton = 1; gui_State = struct('gui_Name', mfilename, ... 'gui_Singleton', gui_Singleton, ... 'gui_OpeningFcn', @simple_gui_OpeningFcn, ... 'gui_OutputFcn', @simple_gui_OutputFcn, ... 'gui_LayoutFcn', [] , ... 'gui_Callback', []); if nargin && ischar(varargin{1}) gui_State.gui_Callback = str2func(varargin{1}); end

if nargout [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:}); else gui_mainfcn(gui_State, varargin{:}); end % End initialization code - DO NOT EDIT

% --- Executes just before simple_gui is made visible. function simple_gui_OpeningFcn(hObject, eventdata, handles, varargin) % This function has no output args, see OutputFcn. % hObject handle to figure % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) % varargin command line arguments to simple_gui (see VARARGIN) % Create the data to plot. handles.peaks=peaks(35); handles.membrane=membrane; [x,y] = meshgrid(-8:.5:8); r = sqrt(x.^2+y.^2) + eps; sinc = sin(r)./r; handles.sinc = sinc; % Set the current data value. handles.current_data = handles.peaks; surf(handles.current_data) % Choose default command line output for simple_gui handles.output = hObject;

% Update handles structure guidata(hObject, handles);

% UIWAIT makes simple_gui wait for user response (see UIRESUME) % uiwait(handles.figure1);

% --- Outputs from this function are returned to the command line. function varargout = simple_gui_OutputFcn(hObject, eventdata, handles) % varargout cell array for returning output args (see VARARGOUT); % hObject handle to figure % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA)

% Get default command line output from handles structure varargout{1} = handles.output;

% --- Executes on button press in pushbutton1. function pushbutton1_Callback(hObject, eventdata, handles) % hObject handle to pushbutton1 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) % Display surf plot of the currently selected data. surf(handles.current_data);

% --- Executes on button press in pushbutton3. function pushbutton3_Callback(hObject, eventdata, handles) % hObject handle to pushbutton3 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) % Display mesh plot of the currently selected data. mesh(handles.current_data);

% --- Executes on button press in pushbutton4. function pushbutton4_Callback(hObject, eventdata, handles) % hObject handle to pushbutton4 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) % Display contour plot of the currently selected data. contour(handles.current_data);

% --- Executes on selection change in popupmenu1. function popupmenu1_Callback(hObject, eventdata, handles) % hObject handle to popupmenu1 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) % Determine the selected data set. str = get(hObject, 'String'); val = get(hObject,'Value'); % Set current data to the selected data set. switch str{val}; case 'Peaks' % User selects peaks. handles.current_data = handles.peaks; case 'Membrane' % User selects membrane. handles.current_data = handles.membrane; case 'Sinc' % User selects sinc. handles.current_data = handles.sinc; end % Save the handles structure. guidata(hObject,handles) % Hints: contents = cellstr(get(hObject,'String')) returns popupmenu1 contents as cell array % contents{get(hObject,'Value')} returns selected item from popupmenu1

% --- Executes during object creation, after setting all properties. function popupmenu1_CreateFcn(hObject, eventdata, handles) % hObject handle to popupmenu1 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles empty - handles not created until after all CreateFcns called

% Hint: popupmenu controls usually have a white background on Windows. % See ISPC and COMPUTER. if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor')) set(hObject,'BackgroundColor','white'); end

[Image Analyst]

I can't tell from looking at that mess. Please use the paper clip icon to attach your m-file and fig-file.