Cannot vertically move markup in cue voice context

[liang seng]

Hi, I am Seng and I am using Lilypond 2.18.2 in Windows 10. I am trying to construct a music with cue notes during multi-measure rests. Here is an example:

\version "2.18.2"

\score { \relative c' { \time 4/4 R1 << 

{ R1-\tweak Y-offset #-5 _\markup A \override TextScript.staff-padding = #4 R1_\markup A }

\new CueVoice { f f } >>  \bar "|." } } 

I inserted the markups (here labelled as "A") under the rests and not in the cue notes since I want them to be aligned centrally in the measure. Since they are too close to the staff, I wish to lower them a bit. However, I can't make the markups move down vertically. Neither the Y-offset tweak or the TextScript staff padding works as shown in the example. Inserting the "Staff", "Score" or "Voice" context before TextScript does not work either. Am I missing something?

Thank you.

Seng Liang.