Alternative brackets don't print

[Qian Li]

Hi, folks. 

I have a multistaff score that requires alternative brackets. I tried the tweak for getting brackets to show in staves below the top staff (below: I may be putting it in the wrong place), but I'm not getting brackets at all. They do print in the individual parts. 

What am I missing? In the attachments, document.ly is the file to run. I also included sop.ly, which is a part that prints correctly. The volta repeat appears on the last page. Thanks.


 \new StaffGroup <<
            \keepWithTag #'score
            \new Staff { \with { \consists "Volta_engraver" } << \global \Soprano >>}
        \new Staff { << \global \Alto>> }
        \new Staff { << \global \Tenor>> }
        \new Staff { << \global \Baritone>> }
        >>

            >>

Qian

document.ly
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content.ly
Description: Text Data

sop.ly
Description: Text Data