Sonar 3.0 does no analysis but displays no errors/warnings - maven

Question

Im using eclipse with m2e for developing and maven 3.0.4 with Sonar 3.0 for analysis.
On the console i get a "Build success" for mvn clean install and a "ANALYSIS SUCCESSFUL, you can browse..." for mvn sonar:sonar. I do not recognize any errors/warnings etc.
In sonar i can see my project, the actual version and build date but there is no analysis.
Are there any reported problems with sonar 3.0 or someone got an idea whats wrong?
Thanks a lot.
pom.xml:
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>DungeonMasterTools</groupId>
<artifactId>DungeonMasterTools</artifactId>
<version>0.0.1-SNAPSHOT</version>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<verbose>true</verbose>
<fork>true</fork>
<executable>${JDK_1_7_HOME}/bin/javac</executable>
<compilerArgument>-verbose</compilerArgument>
<source>1.7</source>
<target>1.7</target>
<meminitial>128m</meminitial>
<maxmem>512m</maxmem>
</configuration>
</plugin>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>sonar-maven-plugin</artifactId>
<version>2.0</version>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.16</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.10</version>
</dependency>
<dependency>
<groupId>com.thoughtworks.xstream</groupId>
<artifactId>xstream</artifactId>
<version>1.4.2</version>
</dependency>
</dependencies>
</project>