2014-01-14 01:08:59,674 [salt.state       ][CRITICAL] Rendering SLS "base:zabbix-agent" failed: Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/salt/utils/templates.py", line 74, in render_tmpl
    output = render_str(tmplstr, context, tmplpath)
  File "/usr/lib/python2.7/dist-packages/salt/utils/templates.py", line 166, in render_jinja_tmpl
    output = jinja_env.from_string(tmplstr).render(**unicode_context)
  File "/usr/lib/python2.7/dist-packages/jinja2/environment.py", line 894, in render
    return self.environment.handle_exception(exc_info, True)
  File "<template>", line 39, in top-level template code
TypeError: unsupported operand type(s) for -: 'StrictUndefined' and 'StrictUndefined'