cadenza when having multiple staffs

[Edmundo Carmona Antoranz]

Hi!

I'm translating Carmen Fantasy by Francois Borne into Lilypond.

I'm writing the score with flute/piano parts and when reaching 2 bars
before Moderato, the flute part has what I think is a cadenza while
the piano part has perfect measures to complete it (rest with
fermata). I tried writing the flute part with a cadenza block but,
when rendering, lilypond is writing the piano and flute parts as if I
hadn't set up the cadenza part. The only thing that is making it look
as if the cadenza is somehow coming into action is that the flute part
has no bar line up until I close the cadenza, both on the flute and
the piano part. So.... how can I make lilypond understand that the
cadenza is covering a single bar from the flute part?

You ca see the part over here:
http://conquest.imslp.info/files/imglnks/usimg/a/ad/IMSLP248733-PMLP403211-Borne_Carmen_Piano.pdf
4th page start of 3rd system.

Thanks in advance.