build a interface using GUIDE - problem

I build a interface using GUIDE of matlab. In this program, I wanted that the string of one push button changed during main callback. I used the command set(handles.cal,'String','XXXX','ForegroundColor',[1 0 0]) at the begin of callback and set(handles.cal,'String','00000','ForegroundColor',[0 0 0]) at the end. The button didn´t change, just when i used breakpoints. What am i doing wrong?

Thanks

Answer 1

[Walter Roberson]

drawnow() after the first set()