Title Word Searching in Content Manager 9

I have a new installation of Content Manager 9 on which I am performing preliminary investigations into code changes needed as a result of a planned upgrade from version 6.  The installation seems to be mostly working and I have partially emulated our legacy systems model of Classifications, Folders etc. Using the desktop interface I have created document records, checked in files etc.  Unfortunately searching by "Title Word" does not work.  The word index was regenerated from Enterprise Studio and if I search the index words they are all visible.  However record searches based on "Title Word" return no results, but searches by "Free Text Title" locate documents without problem.  I also note that the "Structured Title" is blank but I have no idea what that is!

This problem probably stems from an omission or error in configuration but finding it has defeated me.  Can anyone help?