The functions you are referring to are for the list data type, not list boxes. The list data type is a linked list datatype used for creating and storing dynamic lists in memory. List boxes don't have any built in sorting capabilities. Table controls are the only controls I know of with built-in sorting functionality. If you want to stick with a list box and have it sort, you would have to keep the list of values in your program in an array and programmatically determine at what index to insert each value in order to keep them sorted, then use InsertListItem with that index.
Or you could switch to a 1-column table control, which has built-in sorting functionality (SortTableCells) and could be made to look just like a list box.
Best Regards,
Chris Matthews
National Instruments