Error running Solr

I'm trying to install Apache Solr for Plone, via collective.solr.

I've followed the instructions above, and extended my buildout with:

[buildout]
extends =
  buildout.cfg
  https://github.com/Jarn/collective.solr/raw/master/buildout/solr.cfg

[instance]
eggs += collective.solr

bin/buildout runs fine, however, when I try bin/solr-instance fg

I get the following error:

Traceback (most recent call last):
  File "bin/solr-instance", line 114, in <module>
    start(False)
  File "bin/solr-instance", line 43, in start
    stdout=logfp, stderr=logfp).pid
  File "/usr/lib/python2.6/subprocess.py", line 633, in __init__
    errread, errwrite)
  File "/usr/lib/python2.6/subprocess.py", line 1139, in _execute_child
    raise child_exception
OSError: [Errno 2] No such file or directory
Graceful stop

What am I missing / doing wrong?