Lyric extender line bug

[liang seng]

Hi, I am typing a work for soprano by Mozart and I encountered into a 
problem with the lyrics extender lines. I'm using Lilypond 2.7.17 for 
Windows. Here is an extract of the complete file:

\version "2.7.17"
\relative c'
{
\clef treble
 \key f \major
 \time 4/4  \autoBeamOff
g'4 r4 c2\melisma  \break
bes16[ c bes a] bes[ f' e f] e[ f g f] e[ d c bes] a[ bes c d] c4 a16[ bes c 
d]
c4 bes16[ c bes a] bes[ f' e f] e[ f g f] e[ d c bes] a[ bes c d] c4 a16[ 
bes c d] c4 |
d2~d16[ bes f' e] g[ f e f] c2~c16[ a f' e] g[ f e f] bes,2~bes16[ e g f] e[ 
d c bes]
a4\melismaEnd r4 c8[( a]) d[( c]) bes4 a \appoggiatura c16 bes4 a8[( g]) f4 
r4 r2 }

\addlyrics { me, "  " __ psal -- lant ae -- the -- ra cum me. }

Here, the lyric extender line starts from bar 1 until the beginning of bar 9 
and the extender line is meant to be a continous line. However, what 
happened was the line only starts near the middle on bar 4 and is completely 
missing on bar 7. I used break after the 1st bar to show that the extender 
line starts on the 2nd note of bar 2 and not the 1st, as it should.  Why is 
this? Is this a bug and can it be fixed?
This happened in both Windows 98 and Mac. I've heard this bug does not 
appear in Windows XP but since I do not use one, I cannot confirm that.
Any help will be appreciated.
Thank you very much.
Yours sincerely,
Seng Liang