lessc is not found

[sindilevich]

OS: Windows 7 x64
Node.js: 0.6.10
Lessc: 1.2.1 (LESS Compiler) [JavaScript]

When compiling .LESS files with the Ant task the following output is shown:

[lesscss] INFO Running command "lessc" with argument(s): ""-v"".
[lesscss] INFO Failed to determine command version.

Afterwards, no files get transformed to CSS.

Snippet from the buid.xml, used by Ant:

<taskdef name="lesscss" classname="org.znerd.lessc2java.ant.LesscTask">
<classpath>
<pathelement path="${libsdir}/ant/ant.jar"/>
<pathelement path="${libsdir}/commons/commons-exec.jar"/>
<pathelement path="${libsdir}/maven/maven-plugin-api.jar"/>
<pathelement path="${libsdir}/znerd/lessc2java-ant-task.jar"/>
<pathelement path="${libsdir}/znerd/lessc2java-core.jar"/>
<pathelement path="${libsdir}/znerd/znerd-util.jar"/>
</classpath>
</taskdef>

<lesscss dir="${sourcedir}/stylesheets" todir="${destinationdir}/stylesheets"/>

Note, lessc2java-ant-task.jar, lessc2java-core.jar, znerd-util.jar were compiled manually by adding the sources to a Java project in Eclipse, satisfying the dependencies and exporting the relevant packages as above three JAR archives.