Contact name auto-complete

afarr

In the Create Opportunity card there is a Contact field on the second screen.
In Nav 4.03, if we type 'a' then it automatically finds the first contact whose name starts with 'a'.

In NAV 2009 (when the field is made editable), this does not work, even though the properties and code look the same (both in the Create Opportunity form 5126, and in the Opportunity table 5092).

How can we get this to auto-complete?

Thanks.