MATLAB: Getting Error in Matlab GUIDE

Question

I just want to press a button and have 'ok' print to an edit field, but I keep getting the following error after I click the button:

Undefined function or variable 'pushbutton1_Callback'.
Error in gui_mainfcn (line 95)
        feval(varargin{:});
Error in PME_app2 (line 17)
    gui_mainfcn(gui_State, varargin{:});
Error in
matlab.graphics.internal.figfile.FigFile/read>@(hObject,eventdata)PME_app2('pushbutton1_Callback',hObject,eventdata,guidata(hObject)) 
Error while evaluating UIControl Callback.

Code Below

function varargout = PME_app2(varargin)
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @PME_app2_OpeningFcn, ...
                   'gui_OutputFcn',  @PME_app2_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 PME_app2 is made visible.
function PME_app2_OpeningFcn(hObject, eventdata, handles, varargin)
handles.output = hObject;
guidata(hObject, handles);
end
% --- Outputs from this function are returned to the command line.
function varargout = PME_app2_OutputFcn(hObject, eventdata, handles) 
varargout{1} = handles.output;
end  
function pushbutton1_Callback(hObject, eventdata, handles)
    set(handles.edit1,'ok')
  end
% --- Executes during object creation, after setting all properties.
function pushbutton1_CreateFcn(hObject, eventdata, handles)
% hObject    handle to pushbutton1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end
end

Answer 1

Your code for function pushbutton1_Callback would either have to be inside PME_app2.m or else it would have to be in its own pushbutton1_Callback.m file in order to be found.