How to call a method from a mocked interface using EasyMock

I am writing a Junit unit test for a class and I am getting a java.lang.NullPointerException on the following line :

//This line throws an exception expect(lineConfigurationHandlerMock.getDeviceControlHandler().getDeviceParameters(item1)).andReturn(myDeviceParameters);

I think (i am not sure though) that it has something to do with the method (getDeviceControlHandler) that I am calling from within the mocked interface . Because I have added this line of code before the submentioned line:

Assert.assertNotNull(comLineConfigurationHandlerMock.getDeviceControlHandler());

And I am having the following error:

java.lang.AssertionError

I am stuck here and really need some help.

Thanks in Advance.

The thrown Exception:

java.lang.NullPointerException
at de.myproject.project.classTest.testGetParameters(classTest.java:123)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)

Here is the written test:

public class classTest {

// class under test
private classUnderTest classUnderTest;

private LineConfigurationHandler LineConfigurationHandlerMock;

private IMocksControl mocksControl;

List<DeviceParameter> myDeviceParameters;
DeviceParameter deviceParameter1;
DeviceParameter deviceParameter2;

@Before
public void setUp() throws Exception
{
    mocksControl = EasyMock.createControl();

    LineConfigurationHandlerMock = mocksControl.createMock(LineConfigurationHandler.class);

    classUnderTest = new classUnderTest();
    classUnderTest.setLineConfigurationHandler(LineConfigurationHandlerMock);

    String item1 = "item1";

    myDeviceParameters = new ArrayList<DeviceParameter>();
    myDeviceParameters.add(deviceParameter1);
    myDeviceParameters.add(deviceParameter2);

    //Other stuff
}

@Test
public void testGetParameters()
{

    expect(LineConfigurationHandlerMock.getDeviceControlHandler().getDeviceParameters(item1)).andReturn(myDeviceParameters);

    mocksControl.replay();

    //Some code .....
 }
}

Here is the class under test :

    public Class ClassUnderTest
   {
    @Inject
    private LineConfigurationHandler lineConfigurationHandler;

    public List<DeviceParameter> getDeviceParameters(String deviceId) 
    {
        // Method implementation
    }

    @Required
    public void setLineConfigurationHandler(LineConfigurationHandler lineConfigurationHandler)
    {
        this.lineConfigurationHandler = lineConfigurationHandler;
    }
   }

The interface in which the method is declared

public interface LineConfigurationHandler {

DeviceControlHandler getDeviceControlHandler();

//other Method declaration ...
 }

DeviceControlHandler.class

public interface DeviceControlHandler extends Serializable{

List<DeviceParameter> getDeviceParameters(String deviceId);

//Other methods  declaration ...
}