Hi Olu,
You can't sort on a calculated field, because the sort order is determined by the sort of the View. If you want to sort on a calculated column, according to some sort order in an original field, then set the sort order (to actual table fields) on the SORT tab for the browse column.
Much the same with the locator. You can only locate on what is in the database, because it's the database that does the searching. You can specify Locate fields as well on the columns SORT tab.
Cheers
Bruce