Problems with uigetfile('*.txt'), GUIDE push buttons and import data in matlab workspace

Hi

I'm trying to create a GUIDE push button that open a txt file and then load the information in a matrix, the code works perfectly in a matlab document, but in a GUI the data is not loaded in the matlab workspace.

This is the code that I'm using:

% --- Executes on button press in pushbutton1. function pushbutton1_Callback(hObject, eventdata, handles)

[FileName,PathName] = uigetfile('*.txt','Select an txt file');

Signal = importdata([PathName FileName]);

l = length(Signal);

X = Signal(:,1);

Y = Signal(:,2);

Please help me

Thanks

Andrea