Check varaibles from other GUI functions?

Hey all,

I'm trying to set up a GUI for my program and have a few issues. For one part of it, I have 3 radio buttons and a button in a button group. I've set up the functions for the selection change of the radio buttons and i set up a variable to be either 1, 2 or 3 depending on the selection but the button which performs the main part of the program seems to error when i try to read the variable from the radio button selection change function.. Below is my code so far:

% **********************************************  
% OPTION BUTTONS SELECTION..
% **********************************************  
% --- Executes when selected object is changed in uibuttongroup1.
function uibuttongroup1_SelectionChangedFcn(hObject, eventdata, handles)
% CHECK WHICH RADIO BUTTON IS SELECTED..
switch get(eventdata.NewValue,'Tag');
    case 'OptUNFT'
        FiltX = 1;
        msgbox({'UNFILTERED NOTE..', num2str(FiltX)});
    case 'OptISOLATE'
        FiltX = 2;
        msgbox({'ISOLATE NOTE..', num2str(FiltX)});
    case 'OptFTNT'
        FiltX = 3;
        msgbox({'FILTER THE NOTE..', num2str(FiltX)});
end
% END SWITCH..

% **********************************************
% APPLY FILTER BUTTON..
% **********************************************  
% --- Executes on button press in btAPLLYFT.
function btAPLLYFT_Callback(hObject, eventdata, handles)
% hObject    handle to btAPLLYFT (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

switch FiltX;
    case 1
        msgbox('You chose to play the original');
    case 2
        msgbox('You chose to isolate');
    case 3
        msgbox('You chose to filter');
end
% END SWITCH..

By the way, i only have msgbox simply to check things are working as i go.. I don't know enough yet about matlab but in other languages, i'm sure it would be because FiltX is a local variable to that function, Is that right?

If its not this, how can i pass the FiltX value to the button press function..

Excuse my poor terminology haha..

Thanks,

Paul..