Convert PDF to PNG/JPG , using Wand, breaks in production via Gunicorn, fine on debug server

Question

I am trying to convert a PDF to a JPG/PNG via Wand.

This is the code (edit)

os.path.isfile(os.path.join(settings.PROJECT_PATH, "file.pdf"):
    with Image(filename=os.path.join(settings.PROJECT_PATH, "file.pdf", resolution=100) as image:
        image.save(filename=os.path.join(settings.PROJECT_PATH, "file.jpg")

It works perfectly on the local dev server, the dev server on the production server, and also in the manage.py shell (on production server) .

However, when using via my production supervisor/guncicorn setup, I get the following error

DelegateError at /finance/api/v1/receipt/
Postscript delegate failed `/webapps/bab/bab/Beenie-Man-1.pdf': No such file or directory @ error/pdf.c/ReadPDFImage/677

This is the startupscript.

#!/bin/bash

NAME="bab"                                  # Name of the application
DJANGODIR=/webapps/bab/bab             # Django project directory
SOCKFILE=/webapps/bab/run/gunicorn.sock  # we will communicte using this unix socket
USER=bab                                        # the user to run as
GROUP=webapps                                     # the group to run as
NUM_WORKERS=1                                     # how many worker processes should Gunicorn spawn
DJANGO_SETTINGS_MODULE=bab.settings             # which settings file should Django use
DJANGO_WSGI_MODULE=bab.wsgi                     # WSGI module name

echo "Starting $NAME as `whoami`"

# Activate the virtual environment
cd $DJANGODIR
source ../bin/activate
export DJANGO_SETTINGS_MODULE=$DJANGO_SETTINGS_MODULE
export PYTHONPATH=$DJANGODIR:$PYTHONPATH

# Create the run directory if it doesn't exist
RUNDIR=$(dirname $SOCKFILE)
test -d $RUNDIR || mkdir -p $RUNDIR

# Start your Django Unicorn
# Programs meant to be run under supervisor should not daemonize themselves (do not use --daemon)
exec ../bin/gunicorn ${DJANGO_WSGI_MODULE}:application \
  --name $NAME \
  --workers $NUM_WORKERS \
  --user=$USER --group=$GROUP \
  --log-level=debug \
  --bind=unix:$SOCKFILEchris@python:/webapps/bab$ 

When I was running the tests on the production server, with both running the full debug server & the shell, it was being run with the correct user account & correct virtualenv (not that it would work at all without that)

Could it be an environment variable issue though? Or some kind of permission thing?