Maven + Cobertura : Unable to locate [Your Class]. Have you specified the source directory?

Question

I have "MyMath" class with 2 simple methods: "multi" and "add". And test class which will only test multi method.

public class MainTest {

    @Test
    public void testMultiply() {

       MyMath tester = new MyMath();

       // check if multiply(10,5) returns 50
       assertEquals("10 x 5 must be 50", 50, tester.multi(10, 5));
     } 
}

My project structure is:

JenkinsTest/
 src/
  main/Main.java
  math/MyMath.java
  test/MathTest.java

And pom.xml at root of project. I am trying to generate coverage report using cobertura-maven-plugin.

<build>
  <plugins>
    <plugin>
      <groupId>org.codehaus.mojo</groupId>
        <artifactId>cobertura-maven-plugin</artifactId>
        <version>2.6</version>
        <configuration>
          <formats>
           <format>html</format>
           <format>xml</format>
          </formats>
        </configuration>
        <executions>
          <execution>
            <goals>
              <goal>clean</goal>
              <goal>check</goal>
            </goals>
          </execution>
        </executions>
    </plugin>
  </plugins>
</build>  

<dependencies>
  <dependency>
    <groupId>junit</groupId>
      <artifactId>junit</artifactId>
        <version>4.8.1</version>
        <scope>test</scope>
  </dependency>
</dependencies>

And run maven from command line maven cobertura:cobertura

It says 1 Test is run, Cobertura Report generation was successful, Build Success messages. But when I go check target/site/cobertura/index.html, it says "MyMath" class has 100% line coverage (Even though "add" method is not executed). When I click on "MyMath" link, it says "Unable to locate math/MyMath.java. Have you specified the source directory?". I am newbie to Maven and cobertura. Can somebody please kindly guide me to show the coverage result correctly and "Unable to locate" problem. Thank you.

PS: I changed the project structure to Maven Standard Directory Layout as @drembert advice and it works as excepted. But when I clicked the class name, the error: "Unable to locate main/java/MyMath.java. Have you specified the source directory?" is still there.