I am currently making a userform but have now for long time received a strange bug. My userform has a listbox with items and 4 assigned spinbuttons which are machines. Items can only be processed on 1 or 2 machines, and they vary. So I want the spinbuttons to be disabled for those machines that cannot handle an item. But when I perform my userform every second it gets a value to the cells, and every second time the cells are blank. I really dont get it why it Works half of the time?!