Notes are going octaves down

[Jesús Guillermo Andrade]

Hello all! This is my first post and I really can't understand what is
it I am doing wrong. This file shows that I what to repeat a cord and a
separate note in the same staff several times. However, the notes seem
to be interpreted as relative in the sense that they are always going
one octave lower each duration.
Can you help me to fix it?... I haven't found a clear answer on the manual.
Thanks

THIS IS THE FILE
\version "2.11.15"
\include "espanol.ly"
fragA = <<
        {<si do mi> <si do mi> <la do mi> <la do mi>} \\
        {la,,}
        >>

     upper = \relative do''
         {
         \tempo 4=67
         \clef treble
     \key do \major
     \time 4/4

        r1  r1  r1  r1
                
                }

     lower = \relative do' {
        \clef bass
        \key do \major
        \time 4/4
        \fragA \fragB \fragA \fragB
     }

     \score {
        \new PianoStaff <<
           \set PianoStaff.instrumentName = "Piano "
           \new Staff = "upper" \upper
           \new Staff = "lower" \lower
        >>
        \layout { }


END OF FILE

-- 
Jesús Guillermo Andrade (Att.)
Litigation Attorney - Arbitrator
Andrade & Moreno S.C. (https://amlegal.wordpress.com/)