Problem instantiating the AMR encoder

I am using the following code to try to instantiate an AMR encoder instance.
 
It is bombing when I try to instantiate a CMMFFile as a file based data sink. Panic category is USER, Panic code 11. Am I using it correctly? Please help.

    REComSession & connected_session = REComSession::OpenL();

    RImplInfoPtrArray impl_info_arr;
    TUid uid;
    uid.iUid = (TInt32)KMmfUidPluginInterfaceFormatEncode;
    connected_session.ListImplementationsL(uid, impl_info_arr);

/* We know that the 4th one is AMR. */

    CImplementationInformation * p_impl_info = impl_info_arr[3];

    _LIT8(file_name,"c:\\logs\\tryamr\\out.amr");

    MDataSink * my_data_sink = MDataSink::NewSinkL(KUidMmfFileSink, file_name);

    CMMFFormatEncode* amr_encoder = CMMFFormatEncode::NewL(p_impl_info->ImplementationUid(),
                                                            my_data_sink);


I am using KUidMmfFileSink, mentioned in mmfdatasourcesink.hrh.

  Amit