Have you made the control editable, right ckick on the listbox control and make sure 'Editable' is ticked. Now run your program and see if you can enter text at run time.
Have you initialised the item names with any default values? If not try initialising the item names to a 2D size that will be large enough for you're requirements. Once this size is set in edit mode you can't enter data at runtime outside of this initialised area.
