text spanner for pedal

[Stefan Thomas]

Dear Lilypond-users,
I want to create a text-spanner for the pedal sign. I hope  that I can avoid  problems with vertical collisions between pedal-signs and dynamic. Unfortunately the below quoted file doesn't work as expected. I can't see the "Ped" and the line goes down, although it should go up, and the text spanner is above the dynamic.
What can I do?

ped = {
   \textSpannerDown
   \once \override TextSpanner #'bound-details #'left #'text =
      \markup {\musicglyph #"pedal.Ped" } \once \override TextSpanner #'style =
         #'dashed-line
   \once \override TextSpanner #'dash-period = #0.01
   \once \override TextSpanner #'bound-details #'right #'attach-dir = #1
   \once \override TextSpanner #'bound-details #'right #'text =
      \markup { \draw-line #'(0 .-1}
   \once \override TextSpanner #'bound-details #'right #'padding = #-0.5
   }
   \score {\new Staff \relative {\ped g2 \startTextSpan g2 \stopTextSpan }}