OpenCover not recognized as valid coverage engine by C# plugin

     [exec] C:\export\build\hudson-slave\workspace\xxx-sonar\characterencoding\xxx>"C:\Programme\Java\jdk1.6.0_20\bin\java.exe" -Dproject.settings=..\xxx-ams-build\config\sonar-project.properties -classpath "c:\export\build\dotnet\sonar-runner-1.1\lib\sonar-runner.jar";"c:\export\build\dotnet\sonar-runner-1.1\lib\sonar-batch-bootstrapper.jar" "-Drunner.home=c:\export\build\dotnet\sonar-runner-1.1" "-Dproject.home=C:\export\build\hudson-slave\workspace\xxx-sonar\characterencoding\xxx" org.sonar.runner.Main  
     [exec] Runner settings: c:\export\build\dotnet\sonar-runner-1.1\conf\sonar-runner.properties
     [exec] Project settings: C:\export\build\hudson-slave\workspace\xxx-sonar\characterencoding\xxx\..\xxx-ams-build\config\sonar-project.properties
     [exec] Runner version: 1.1
     [exec] Server: http://SERVER:8080/sonar
     [exec] Work directory: C:\export\build\hudson-slave\workspace\xxx-sonar\characterencoding\xxx\.sonar
     [exec] [INFO]  Database dialect class org.sonar.jpa.dialect.MySql
     [exec] [INFO]  Initializing Hibernate
     [exec] [INFO]  The following 'sln' file has been found and will be used: C:\export\build\hudson-slave\workspace\xxx-sonar\characterencoding\xxx\Xxx Release 2.10.sln
     [exec] [INFO]  The project 'Xxx.Core.Tests' has been qualified as a test project.
     [exec] [INFO]  -------------  Analyzing Xxx
     [exec] [INFO]  Selected quality profile : [name=ams-dotnet-default,language=cs]
     [exec] [INFO]  Configure maven plugins...
     [exec] [INFO]  Compare to previous analysis
     [exec] [INFO]  Compare over 5 days (2011-11-26)
     [exec] [INFO]  Compare over 30 days (2011-11-01)
     [exec] [INFO]  Initializer CSharpProjectInitializer...
     [exec] [INFO]  Initializer CSharpProjectInitializer done: 0 ms
     [exec] [INFO]  Sensor org.sonar.plugins.csharp.core.CSharpSourceImporter@1412c18...
     [exec] [INFO]  Sensor org.sonar.plugins.csharp.core.CSharpSourceImporter@1412c18 done: 18250 ms
     [exec] [INFO]  Sensor com.sonar.plugins.csharp.squid.C@e79eb3...
     [exec] [INFO]  Sensor com.sonar.plugins.csharp.squid.C@e79eb3 done: 78310 ms
     [exec] [INFO]  Sensor org.sonar.plugins.csharp.gallio.GallioSensor@2df...
     [exec] [ERROR]  Tried to get a CoverageTool with name OpenCover, but such a tool is not supported.
     [exec] Exception in thread "main" org.sonar.batch.bootstrapper.BootstrapException: java.lang.IllegalArgumentException: No enum const class org.sonar.dotnet.tools.gallio.CoverageTool.OPENCOVER
     [exec] 	at org.sonar.runner.Runner.delegateExecution(Runner.java:155)
     [exec] 	at org.sonar.runner.Runner.execute(Runner.java:58)
     [exec] 	at org.sonar.runner.Main.main(Main.java:52)
     [exec] Caused by: java.lang.IllegalArgumentException: No enum const class org.sonar.dotnet.tools.gallio.CoverageTool.OPENCOVER
     [exec] 	at java.lang.Enum.valueOf(Enum.java:196)
     [exec] 	at org.sonar.dotnet.tools.gallio.CoverageTool.valueOf(CoverageTool.java:32)
     [exec] 	at org.sonar.dotnet.tools.gallio.CoverageTool.findFromName(CoverageTool.java:86)
     [exec] 	at org.sonar.dotnet.tools.gallio.GallioCommandBuilder.setCoverageTool(GallioCommandBuilder.java:153)
     [exec] 	at org.sonar.plugins.csharp.gallio.GallioSensor.analyse(GallioSensor.java:105)
     [exec] 	at org.sonar.batch.phases.SensorsExecutor.execute(SensorsExecutor.java:64)
     [exec] 	at org.sonar.batch.phases.Phases.execute(Phases.java:93)
     [exec] 	at org.sonar.batch.bootstrap.ProjectModule.doStart(ProjectModule.java:143)
     [exec] 	at org.sonar.batch.bootstrap.Module.start(Module.java:89)
     [exec] 	at org.sonar.batch.bootstrap.BatchModule.analyze(BatchModule.java:110)
     [exec] 	at org.sonar.batch.bootstrap.BatchModule.analyze(BatchModule.java:105)
     [exec] 	at org.sonar.batch.bootstrap.BatchModule.doStart(BatchModule.java:100)
     [exec] 	at org.sonar.batch.bootstrap.Module.start(Module.java:89)
     [exec] 	at org.sonar.batch.bootstrap.BootstrapModule.doStart(BootstrapModule.java:96)
     [exec] 	at org.sonar.batch.bootstrap.Module.start(Module.java:89)
     [exec] 	at org.sonar.batch.Batch.execute(Batch.java:74)
     [exec] 	at org.sonar.runner.Launcher.executeBatch(Launcher.java:60)
     [exec] 	at org.sonar.runner.Launcher.execute(Launcher.java:53)
     [exec] 	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     [exec] 	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
     [exec] 	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
     [exec] 	at java.lang.reflect.Method.invoke(Method.java:597)
     [exec] 	at org.sonar.runner.Runner.delegateExecution(Runner.java:152)
     [exec] 	... 2 more
     [exec]