Dynamics not correctly aligned

[David Sumbler]

I am a new user of Lilypond, using v. 2.14.2 on Ubuntu 12.04.  I have
read the Learning Manual and Notation Reference twice each, and most of
the other documentation at least once.

Having set two pieces (one for solo marimba, and one for flute and
piano), I hoped that I had reached the stage of being able to fine tune
the appearance, but stumbled at almost the first hurdle!

My first problem concerns the second piece.  If I include the piano
dynamics separately from the notes, as suggested in section A.2.4 (Piano
Centred Dynamics) of the Learning Manual, they do not line up correctly
with the dynamics in the flute part, which I have attached to the notes.

For instance, with:

\version "2.14.2"

<<
  \new Staff = "flute" \relative c''' { c1\p c\f }
  \new PianoStaff <<
    \new Staff \relative c'' { c1 c }
    \new Dynamics { s1\p s\f }
    \new Staff \relative c { \clef bass c1 c }
    >>
>>

the dynamics in the piano part appear slightly further to the left than
those in the flute part do.  I get the same result (disregarding the
change in vertical alignment) with:

\version "2.14.2"

dynamics = { s1\p s\f }

<<
  \new Staff = "flute" \relative c''' { c1\p c\f }
  \new PianoStaff <<
    \new Staff << \relative c'' { c1 c } \dynamics >>
    \new Staff \relative c { \clef bass c1 c }
    >>
>>

In the actual piece I have set, the misplaced piano dynamics actually
collide with the preceding bar-lines, although that does not happen in
the above brief examples.

What am I doing wrong here?  Thanks in advance for any help you can
offer.


David