Cobertura is not showing proper coverage for few classes

Question

<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.19.1</version>
<configuration>
<argLine>-noverify</argLine> 
<redirectTestOutputToFile>true</redirectTestOutputToFile>
</configuration>
</plugin>

The above plugin is used to generate cobertura report. The cobertura coverage percent fluctuates every time I build my project. While debugging control is going to each and every line . But the coverage report is improper.