Getting warnings when calling CSS validator from the command line

Hi,

I have a local install of the CSS validator and when calling it from the 
command line I appear to be getting only errors in the output and not 
warnings in cases where I should be getting both.

I'm testing this with 
http://css-validation.simplytestable.com/one-error-one-warning.html. 
Testing with the online CSS validator returns one warning and one error:

http://jigsaw.w3.org/css-validator/validator?uri=http%3A%2F%2Fcss-validation.simplytestable.com%2Fone-error-one-warning.html&warning=2

Validating the same URL from the command line returns just one error and 
no warnings. This seems to be the case regardless of the value passed 
for the 'warning' parameter. This also seems to be the case regardless 
of the output format.

An example of the command I am issuing is:

java -jar /home/example/css-validator.jar -output ucn -warning 2 
"http://css-validation.simplytestable.com/one-error-one-warning.html"

This returns output of the form:

{vextwarning=false, output=ucn, lang=en, warning=2, medium=all, 
profile=css3}
<?xml version='1.0' encoding="utf-8"?>
<observationresponse 
xmlns="http://www.w3.org/2009/10/unicorn/observationresponse" 
ref="http://css-validation.simplytestable.com/one-error-one-warning.html" date="2013-04-04T08:18:12Z" 
xml:lang="en">

<message type="error" 
ref="http://css-validation.simplytestable.com/assets/css/one-error-one-warning.css">
     <context line="2">.hide-text</context>
     <title>
         Value Error :  font (nullfonts.html#propdef-font)
         0 is not a font-weight value :
         0 / 0 a
     </title>
</message>

</observationresponse>

As you can see, only an error is reported and no warnings are reported.

I am able to get vendor extension issues reported as warnings when 
calling from the command line. But other warnings, as you can see from 
the above output, are missing.

Should I be able to get warnings reported in the output when calling 
from the command line similar to the warnings I receive from the online 
CSS validator? If so, what parameters should I be using such that the 
warnings are returned?

Kind regards,
Jon Cram