deploying third party artifacts: "Unsupported Protocol: 'dav'"

[Lustig, Marc (Allianz Deutschland AG)]

We are having trouble to deploy 3rd party-artefacts using mvn
deploy-plugin.

I followed the instructions located here
http://maven.apache.org/archiva/guides/getting-started/maven-configurati
on.html

but the result is 

[ERROR] BUILD ERROR
[INFO]
------------------------------------------------------------------------
[INFO] Error deploying artifact: Unsupported Protocol: 'dav': Cannot
find wagon which supports the requested protocol: dav

Component descriptor cannot be found in the component repository:
org.apache.maven.wagon.Wagondav.
[INFO]
------------------------------------------------------------------------
[DEBUG] Trace
org.apache.maven.lifecycle.LifecycleExecutionException: Error deploying
artifact: Unsupported Protocol: 'dav': Cannot find wagon which supports
the requested protocol: dav


here is the pom.xml used for upload:

<project>
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.example</groupId>
   <artifactId>webdav-deploy</artifactId>
   <packaging>pom</packaging>
   <version>1</version>
   <name>Webdav Deployment POM</name>
   
   
   <build>
      <extensions>
         <extension>
            <groupId>org.apache.maven.wagon</groupId>
            <artifactId>wagon-webdav</artifactId>
            <version>1.0-beta-2</version>
         </extension>
      </extensions>
   </build>
   
</project>