Suddenly, not getting any output score

[Alasdair McAndrew]

I'm just getting back into using Lilypond after some years away 
from it.  And I'm trying to first typeset a baroque duet for two 
melody instruments  - which should just be a matter of copying 
down note names - and then transposing the piece for use by 
different instruments.

I got the first part OK.

But then, after trying to put in a few "transpose" directives (and 
taking them out again), I have the piece as I first had it - 
except that when I run lilypond, it now only produces midi output, 
and not the pdf score.

I tried running lilypond with

"lilypond --loglevel=DEBUG mymusic.ly"

which shows no errors, but it only produces the midi output, and 
not the pdf score.  So something I've done seems to be inhibiting 
the score production.

I'm not quite sure what information I should provide (other than 
my whole file), but are there any known reasons for this?

Thanks,
Alasdair

--
Alasdair McAndrew
http://numbersandshapes.net