TC5 + svn + maven2 + build number problems

Hi there we are using maven-buildnumber-plugin but are having some issues, because when TeamCity 5.0 downloads our code from Subversion it doesnt seem to create a working copy, because of this Maven cannot use Subversion to get the build number and so our builds in TeamCity are failing. How can I fix this please?

Details of the maven plugin are as follows -

<plugin>
          <groupId>org.codehaus.mojo</groupId>
          <artifactId>maven-buildnumber-plugin</artifactId>
          <version>0.9.6</version>
          <executions>
            <execution>
              <phase>validate</phase>
              <goals>
                <goal>create</goal>
              </goals>
            </execution>
          </executions>
          <configuration>
            <doCheck>true</doCheck>
            <doUpdate>true</doUpdate>
          </configuration>
        </plugin>