Code Coverage for Catch Blocks using EclEMMA

I have catch block, i want to execute the catch block. My Class file is,

    public class TranscoderBean implements TranscoderLocal {
    public byte[] encode(final Collection<?> entitySet) throws TranscoderException {
        Validate.notNull(entitySet, "The entitySet can not be null.");
        LOGGER.info("Encoding entities.");
        LOGGER.debug("entities '{}'.", entitySet);

        // Encode the Collection
        MappedEncoderStream encoderStream = null;
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        try {
            // Create the encoder and write the the DSE Logbook messgae
            encoderStream = new MappedEncoderStream(outputStream, this.encoderVersion);
            encoderStream.writeObjects(new ArrayList<Object>(entitySet), false);
            encoderStream.flush();
        }
        catch (Exception e) {
            LOGGER.error("Exception while encoding entities", e);
            throw new TranscoderException("Failed to encode entities", e);
        }
        finally {
            if (encoderStream != null) {
                try {
                    encoderStream.close();
                }
                catch (IOException e) {
                    LOGGER.error("Exception while closing the endcoder stream.", e);
                    throw new TranscoderException("Failed to close encoder stream", e);
                }
            }
        }
     }

My Test Class file is,

public class TranscoderBeanTest {


    @Mock
    MappedEncoderStream MappedEncoderStream;
    @Test
    public void encodeTest() throws TranscoderException {
        List<Object> entitySet = new ArrayList<Object>();
        FlightLog log1 = new FlightLog();
        log1.setId("F5678");
        log1.setAssetId("22");

        FlightLog log2 = new FlightLog();
        log2.setId("F5679");
        log2.setAssetId("23");
        entitySet.add(log1);
        entitySet.add(log2);

        MockitoAnnotations.initMocks(this);
        try {
            Mockito.doThrow(new IOException()).when(this.techLogsMappedEncoderStream).close();

            Mockito.doReturn(new IOException()).when(this.techLogsMappedEncoderStream).close();
        }
        catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        byte[] encode = this.fixture.encode(entitySet);
        Assert.assertNotNull(encode);
    } 
}

I have tried, Mockito.doThrow and Mockito.doReturn methods but still the catch block is not executed. What am doing wrong.