weird horizontal-spacing problem

[David Griffel]

I'm a beginner with lilypond, have learnt a lot from the documentation, 
but here's a problem I can't solve.

I'm writing the score of a piano song, with lyrics between the staves. 
The music has verbose performance instructions at various points, which 
I've done like this:

         f bes \emptyText ees
         ^ "Immer staerker und lebhafter"
         f

Mostly this works fine.  But the text above appears in the last line of 
the song, and the result is a really ugly large horizontal space in the 
music, see    http://www.zen22109.zen.co.uk/screenshot-1.jpg

For the .ly file see  http://www.zen22109.zen.co.uk/geheim__.ly
I've marked the relevant bit with %  HERE IS THE PROBLEM

I've searched the online documentation, and the only helpful thing I've 
found is \emptyText, which doesn't work here, and a statement somewhere 
that lilypond has no way of adjusting horizontal spacing (!!)

Comments and attempts to diagnose:

*  inserting text earlier in the score works perfectly

*  the problem does not go away if I use \ragged-right, see 
http://www.zen22109.zen.co.uk/screenshot-2.jpg

*  the problem goes away if I don't print the lyrics: spacing is then OK

*  the problem goes away if I comment out the text: % ^ "..".
So it's not purely a lyrics problem.

*  I don't use  \lyricsto  because the upper stave has some sections in 
a single voice and other sections in two voices, so there's no unique 
voice to attach the lyrics to.

I hope it's not some really stupid beginner's mistake . . . well 
actually I hope it _is_, because then it'll be easy to fix.  Any help 
will be much appreciated,

David Griffel