Can't find audio files to be played randomly - folder name not defined

Hi all,
I’m completely new and I’m struggling with something probably very basic. I am trying to play random .wav files and collect a response for each file. Something keeps going wrong and I don’t know what it is. In the sound properties I specified the folder where to look for the file writing $ and the name of the folder and I chose “set the file at every repeat”. In the trial properties I specified the conditions, and specifically the name of 3 audio files that should be played in random order (they are 120 in the final version but I wanted to make it work with a selection).

The software runs through the intro section but crashes at the trial section, giving the following message:
PS the name “pairs” that is not defined is the name of the folder where the audio files are.

Running: /Users/lucacilibrasi/Documents/Cambridge/psychopy/exp0_lastrun.py

saved data to u’/Users/lucacilibrasi/Documents/Cambridge/psychopy/data/1_exp0_2016_Sep_21_1434.csv’
Traceback (most recent call last):
File “/Users/lucacilibrasi/Documents/Cambridge/psychopy/exp0_lastrun.py”, line 162, in
sound_1.setSound(pairs)
NameError: name ‘pairs’ is not defined

Hope somebody can help, thank you!!

Hi actually solved it! the problem is that the first coloum in the trial properties should have been the name “pairs”. All sorted!