LandingPage is not a valid ObjectType.

[V-Kevin]

While I am trying to get LandingPage By SOPA API.it throw exception ： LandingPage is not a valid ObjectType.

Below is my code snippet: String[] testArray = { "Id" };

    try{
        System.out.println( "****************** STARTING EMAIL RETRIEVAL TEST ******************" );            
        RetrieveRequest retrieveRequest = new RetrieveRequest();
        retrieveRequest.setObjectType( "LandingPage" );
        java.util.List<String> list = Arrays.asList( testArray );
        retrieveRequest.getProperties().addAll( list );
        RetrieveRequestMsg retrieveRequestMsg = new RetrieveRequestMsg();
        retrieveRequestMsg.setRetrieveRequest( retrieveRequest );
        RetrieveResponseMsg retrieveResponseMsg = stub.retrieve( retrieveRequestMsg );
        System.out.println( "[overall status message2] " + retrieveResponseMsg.getOverallStatus() );
        java.util.List <APIObject> apiObjectArray = retrieveResponseMsg.getResults();
        System.out.println("aoiObjArray::"+apiObjectArray);

        for ( APIObject dumpStepThrough : apiObjectArray )
        {
            if ( dumpStepThrough instanceof LandingPage )
            {
                LandingPage result = ( LandingPage )dumpStepThrough;
                System.out.println( "[landingpage Id]   " + result.getId());
            }
        }
        System.out.println( "****************** ENDING EMAIL RETRIEVAL TEST ******************" );
    } catch ( Exception e ){ 
        e.printStackTrace();
    }