Maven2 Multiproject Cobertura Reporting Problems During mvn site Build

<build>
    <pluginManagement>
        <plugins>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>cobertura-maven-plugin</artifactId>
                <inherited>true</inherited>
                <executions>
                    <execution>
                        <id>clean</id>
                        <goals>
                            <goal>clean</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </pluginManagement>
</build>
<reporting>
    <plugins>
        <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>cobertura-maven-plugin</artifactId>
            <inherited>true</inherited>
        </plugin>
    </plugins>
</reporting>

<reporting>
    <plugins>
        <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>cobertura-maven-plugin</artifactId>
        </plugin>
    </plugins>
</reporting>

...
[INFO] [cobertura:instrument]
[INFO] Cobertura 1.9 - GNU GPL License (NO WARRANTY) - See COPYRIGHT file
Instrumenting 3 files to C:workspacessandboxCommonJsftargetgenerated-classescobertura
Cobertura: Saved information on 3 classes.
Instrument time: 186ms

[INFO] Instrumentation was successful.
...
[INFO] Generating "Cobertura Test Coverage" report.
[INFO] Cobertura 1.9 - GNU GPL License (NO WARRANTY) - See COPYRIGHT file
Cobertura: Loaded information on 3 classes.
Report time: 481ms

[INFO] Cobertura Report generation was successful.

<build>
  ...
    <plugins>
    ...
      <plugin>
        <inherited>true</inherited>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>cobertura-maven-plugin</artifactId>
        <version>${cobertura.plugin.version}</version>
      </plugin>
    </plugins>
  </build>