Context menus didn't show where it should be.

I use a ButtonDownFcn of axes1 to generate a context.However,all seems to be right except that the context doesn't show where the mouse click on.In fact,it always shows on the left buttom of the figure no matter where I click on the axes.The figure‘s units is set to normalized.

function axes1_ButtonDownFcn(hObject, eventdata, handles)  
if strcmp(get(gcf,'SelectionType'),'alt') % Right click the mouse
   pos=get(gcf,'CurrentPoint');
   set(handles.Context_Menus,'position',[pos(1,1),pos(1,2)],'visible','on')
end