Tuplet bracket visibility

[Peter O'Doherty]

Hi,
Lilypond seems to be selective in applying the \override command to 
allow bracket visibility (which I have in the layout section as below). 
Is there another way to force it to always do so?
Thanks again,
Peter


 \layout {
     \context {
       \Score
       \override TupletBracket #'bracket-visibility = ##t
       \override TupletNumber #'text = #tuplet-number::calc-fraction-text
     }
   }