Cobertura generates lots of errors and no output

Question

I have included Cobertura in my Maven project using this guide. I added the following to my pom.xml:

  <plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>cobertura-maven-plugin</artifactId>
    <version>2.6</version>
    <configuration>

      <formats>
        <format>html</format>       
        <format>xml</format>
      </formats>
      <outputDirectory>${project.build.directory}/surefire-reports/cobertura</outputDirectory>      
      <instrumentation>
        <ignoreTrivial>true</ignoreTrivial>         
        <ignores>
          <ignore>org.slf4j.Logger.*</ignore>       
        </ignores>
        <excludes>  
        </excludes>
      </instrumentation>
    </configuration>
    <executions>
      <execution>
        <phase>package</phase>          
        <goals>
          <goal>cobertura</goal>
        </goals>
      </execution>
    </executions>
  </plugin>

When I run the build I get errors like this:

[cobertura] WARN  [main] net.sourceforge.cobertura.instrument.CoberturaInstrumenter - Unable to instrument file C:\MYSELF\programing\java\AutoCall\AutoClient\target\generated-classes\cobertura\cz\autoclient\autoclick\ComparablePixel.class
java.lang.IllegalArgumentException
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at net.sourceforge.cobertura.instrument.CoberturaInstrumenter.instrumentClass(CoberturaInstrumenter.java:147)
    at net.sourceforge.cobertura.instrument.CoberturaInstrumenter.instrumentClass(CoberturaInstrumenter.java:121)
    at net.sourceforge.cobertura.instrument.CoberturaInstrumenter.addInstrumentationToSingleClass(CoberturaInstrumenter.java:234)
    at net.sourceforge.cobertura.instrument.Main.addInstrumentationToSingleClass(Main.java:298)
    at net.sourceforge.cobertura.instrument.Main.addInstrumentation(Main.java:307)
    at net.sourceforge.cobertura.instrument.Main.parseArguments(Main.java:399)
    at net.sourceforge.cobertura.instrument.Main.main(Main.java:421)

They all appear to be in strange folder ProjectName\target\generated-classes\cobertura which I definitely did not create. My report looks like this:

When I press Run All Tests I just get the same errors as during build.

What is it? Report from Cobertura is required for my project, I must make it work.