Creating midi file that is not empty

[Claire Meyer]

Hi everyone,

I have read the documentation and have gone through the archives of the
mailing list, and don't understand what I've got wrong. The midi file I
generate is empty and doesn't contain music. My .ly file is as follows :

\score {
     {c''4 c'' c''}
     \layout {}
     \midi {\context {
         \Score tempoWholesPerMinute = #(ly:make-moment 120 4)
         }
     }
}

The terminal doesn't give any errors at compilation, and says that :

Requested buffer size 32768, fragment size 8192
ALSA pcm 'default' set buffer size 32768, period size 8192 bytes
Playing pianoClarinetUriTzion.midi
MIDI file: pianoClarinetUriTzion.midi
Format: 1  Tracks: 2  Divisions: 384
Sequence:
Text: creator:
Text: GNU LilyPond 2.20.0
Track name: \new:
No instrument mapped to tone bank 0, program 0 - this instrument will not
be heard
No pre-resampling cache hit
Last 1 MIDI events are ignored
Playing time: ~4 seconds
Notes cut: 0
Notes lost totally: 0

When I try to read my midi file. Can someone help me ?

Thanks in advance,
Claire