I'm using sonar and cobertura (for code coverage). I'm baffled with the problem I'm facing. If I run 

```
mvn sonar:sonar

```

I saw the following error during executions

```
[INFO]
[INFO] <<< cobertura-maven-plugin:2.5.1:cobertura (default-cli) @ hss-core <<<
[INFO]
[INFO] --- cobertura-maven-plugin:2.5.1:cobertura (default-cli) @ hss-core ---
[INFO] Error occurred during initialization of VM
Too small initial heap

[ERROR] Error in Cobertura Report generation: Unable to generate Cobertura Report for project.
org.apache.maven.plugin.MojoExecutionException: Unable to generate Cobertura Report for project.
        at org.codehaus.mojo.cobertura.tasks.ReportTask.execute(ReportTask.java:93) 

```

if I run the cobertura plugin directly using the following

```
mvn cobertura:cobertura

```

There is no error as above, and display the following output, which I assume was the expected output.

```
[INFO]
[INFO] <<< cobertura-maven-plugin:2.5.1:cobertura (default-cli) @ hss-core <<<
[INFO]
[INFO] --- cobertura-maven-plugin:2.5.1:cobertura (default-cli) @ hss-core ---
[INFO] Cobertura 1.9.4.1 - GNU GPL License (NO WARRANTY) - See COPYRIGHT file
Cobertura: Loaded information on 39 classes.
Report time: 1035ms

```

I have set the MAVEN\_OPTS (MAVEN\_OPTS=-Xms512m) environment variable, but still getting the error.

Can anyone tell me what went wrong, and how to fix this?