How to use variable of another function with a function? switch-case. Matlab Gui

I want to call a variable in a popupmenu from a button. I mean, popup value will only show the current status and when I press the button it will operate according to the popup menu status. Here is my code, i get "Undefined function or variable 'popupmenu4value" error when i press the button.

 function pushbutton1_Callback(hObject, eventdata, handles)
 switch popupmenu4value
    case 'A'
%function of A
    case 'B'
%function of B
 function popupmenu4_Callback(hObject, eventdata, handles)
 contents = get(handles.popupmenu4,'String'); 
 popupmenu4value = contents{get(handles.popupmenu4,'Value')};

I found axesMenuToolbar in gui examples but it is written in older verison and i can't use it. what i want is exactly this "axesMenuToolbar" help gui. thanks in advance..

[Walter Roberson]

duplicates http://www.mathworks.co.uk/matlabcentral/answers/85444-how-to-read-popup-menu-string-and-use-it-in-another-button-function-matlab-gui