set input value from GUI into global variable in matlab

Question

i have problem with matlab gui that when i set it global variable not work and not shown in work space table also i would to use it in more than function how to use it i tryed this code but not worked the idea that i set poin x , y , z then i want to made offset with this points so i need to use it as global variables

function pushbutton2_Callback(hObject, eventdata, handles)
global Ref_x;
global Ref_y;
global Ref_z;
px=str2double(get(handles.pos_x,'string'))+Ref_x;
py=str2double(get(handles.pos_y,'string'))+Ref_y;
pz=str2double(get(handles.pos_z,'string'))+Ref_z;