When typing the AKA name, you must type in last name, first name format and only then the "new" name shows up in the search field. (Nothing shows up if you type first name then last name). There is no way to know which person from the list is the one you need without going to the pullout on each one until you find the correct person.
This feature does exist. For example, I have a client with the first name: Robert (AKA is Bob), I type "Bob" in the search and it comes up (So you do not need the last name. If you use the last name, the last name goes first, then the "aka" name.