How can I get an XML Site with Maven or Ant?

I am trying to get the revision of the last stable hudson build in order th build a stable release. Currently I use the Hudson API and Maven with Ant:

   <plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-antrun-plugin</artifactId>
<executions>
    <execution>
        <id>download-files</id>
        <phase>prepare-package</phase>
        <goals>
            <goal>run</goal>
        </goals>
        <configuration>
            <target>
                <get src="http://hudson/job/CI/lastSuccessfulBuild/api/xml?xpath=/freeStyleBuild/changeSet/revision/revision"
                     dest="C:/test.xml"
                />
             </target>
         </configuration>
     </execution>
 </executions>

But ant doesn't get the xml... Has anybody an idea?