Cannot get Cobertura coverage report - maven

Question

I use SonarQube 4.5.2, with Maven in an Eclipse project. Here are fragments from my POM:
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>cobertura-maven-plugin</artifactId>
<version>${cobertura.maven.plugin.version}</version>
<configuration>
<instrumentation>
<ignores>
<ignore>org.xxx.xxx.gwt.xxx.common.client.ui.overlay.xxx.gen.*</ignore>
</ignores>
<excludes>
<exclude>org/xxx/xxx/gwt/xxx/common/client/ui/overlay/xxx/gen/**/*.class</exclude>
<exclude>org/xxx/xxx/gwt/xxx/common/client/ui/overlay/xxx/gen/**/*Test.class</exclude>
</excludes>
</instrumentation>
</configuration>
<executions>
<execution>
<goals>
<goal>clean</goal>
<goal>cobertura</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.13</version>
<configuration>
<argLine>-Xmx512M -XX:MaxPermSize=128M</argLine>
</configuration>
</plugin>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>gwt-maven-plugin</artifactId>
<version>${gwtplugin.version}</version>
<configuration>
<gwtSdkFirstInClasspath>true</gwtSdkFirstInClasspath>
<extraJvmArgs>-Xss2M -XX:MaxPermSize=512M -Xmx2048m -Xdebug </extraJvmArgs>
<!-- <extraJvmArgs>-Xss2M -XX:MaxPermSize=400M -Xms700M -Xmx1024M</extraJvmArgs> -->
<hostedWebapp>web</hostedWebapp>
<modules>
<module>org.xxx.xxx.gwt.xxx.xxx.Module1</module>
<module>org.xxx.xxx.gwt.xxx.xxx.Module2</module>
<module>org.xxx.xx.gwt.xxx.xxx.Module3</module>
</modules>
<compileReport>true</compileReport>
<strict>true</strict>
<runTarget>app.html</runTarget>
</configuration>
<executions>
<execution>
<goals>
<goal>compile</goal>
<goal>test</goal>
</goals>
</execution>
</executions>
<dependencies>
<dependency>
<groupId>com.google.gwt</groupId>
<artifactId>gwt-user</artifactId>
<version>${gwt.version}</version>
</dependency>
<dependency>
<groupId>com.google.gwt</groupId>
<artifactId>gwt-servlet</artifactId>
<version>${gwt.version}</version>
</dependency>
</dependencies>
</plugin>
<profile>
<id>sonar</id>
<properties>
<!-- SonarQube enables the appropriate plugin from the coverage report that already finds -->
<!-- <sonar.java.coveragePlugin>cobertura</sonar.java.coveragePlugin> -->
<sonar.dynamicAnalysis>reuseReports</sonar.dynamicAnalysis>
<!-- <sonar.jacoco.reportPath>${project.basedir}/../target/jacoco.exec</sonar.jacoco.reportPath> -->
<sonar.jdbc.url>jdbc:mysql://localhost:3306/sonar</sonar.jdbc.url>
<sonar.jdbc.username>username</sonar.jdbc.username>
<sonar.jdbc.password>password</sonar.jdbc.password>
<sonar.jdbc.driver>com.mysql.jdbc.Driver</sonar.jdbc.driver>
<sonar.host.url>http://localhost:9000/</sonar.host.url>
<sonar.projectVersion>2.0</sonar.projectVersion>
<sonar.language>java</sonar.language>
<sonar.sourceEncoding>UTF-8</sonar.sourceEncoding>
<sonar.sources>src/main/java</sonar.sources>
<sonar.inclusions>(...)</sonar.inclusions>
</properties>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-failsafe-plugin</artifactId>
<version>2.18.1</version>
</plugin>
<plugin>
<groupId>org.codehaus.sonar</groupId>
<artifactId>sonar-maven3-plugin</artifactId>
<version>4.5.2</version>
</plugin>
</plugins>
</build>
</profile>
Now when I run mvn clean -Psonar test cobertura:cobertura sonar:sonar, I would expect to visit http://localhost:9000/ and check the code coverage widget. But it shows 0%. Does anyone has an idea why is this happen?
Java version 1.6.0_45.
Eclipse Luna.
SonarQube 4.5.2.