How to insert Vietnamese in listbox GUI matlab?

Hi everyone!

My problem is:

I have a GUI contains a listbox. And, now, i want to insert a struct contains Vietnamese into the listbox. I used command "set". But, it is mistake in font (picture below)

Vietnamese = {'cáp xoắn 7 sợi','khuôn đo độ sụt bê tông hình côn','sự mài mòn'} % a variable contains Vietnamese symbols
set(handles.listword,'String',Vietnamese) % set string to listbox

What can i do to solve this prolem?

thank in advance!