Neither in my project nor in  http://jqueryui.com/selectable/ can I use the up and down arrows to navigate through a list.

I have looked through the API to see if I haven't enabled it but there are no options for keyboard even though my first link says:

• keyboard (Boolean | default: true)

  Disables or enables keyboard selection (this does not affect mouse+key combinations).

What am I doing wrong since I can't use the keys?