Adding a field to the field-definitions using Diamond Access

I hope anybody can help me quick, as my custommer is waiting for his
software...

For the last couple of hours I've been trying to update a Access-table using
Diamond Access. I have an aditional field that the program should add to the
existing database. However I had no luck yet. Even though I don't get any
errors from the program, the update is not executed to the database itself.

After using
  With DAOTable1.FieldDefs.AddFieldDef DO
     Begin
       Name ...
       ....
     End;
  DAOTable1.FieldDefs.Update;

and closing the database, the exta field is not added to the field
definition.

I probably am forgetting one more command, but I haven't got a clue which
one. I hope you can help me

Thanks !

Marc van Leeuwen