Problem with Simple Animation

I am trying to follow the pattern shown in SimpleAnimation.java to create an animated display of my own data set, but I appear to be making a subtle mistake in setting up my data structures. 

Basically, I create two 2D FieldImpl's mapping ( (lat, lon) -> temp) ), then
create a new FieldImpl mapping (time -> ( (lat, lon) -> temp) ). I use the setSample method to make my first 2D field correspond to time 0, and the second to time 1. Then I animate the result, and turn on stepping ( I think).
The first frame displays properly, and the legend in the lower right hand corner says 1 of 2, but the second frame doesn't ever appear.
Code is below: if anyone sees whatever obvious thing it is I've missed I'd appreciate it. 

        Edward
DisplayImplJ2D makeAnimationDisplay(FieldImpl displayField1, FieldImpl displayField2) throws VisADException, java.rmi.RemoteException 
    {
       // get the FunctionType of the flatfield
        FunctionType myFuncType = (FunctionType)displayField1.getType();
        RealType rangeType = (RealType) myFuncType.getRange();
        RealTupleType domainType = (RealTupleType) myFuncType.getDomain();
        RealType domainComponents[] = domainType.getRealComponents();

        // create a new FieldImpl containing the two slices as alternate times
        RealType time = RealType.Time;
        RealTupleType timeTupleType = new RealTupleType(time);
        FunctionType animatedFuncType = new FunctionType(time, myFuncType);

        // fake up a time domain
        float timeSamples[][] = { {0, 1} };
Gridded1DSet timeSet = new Gridded1DSet(RealType.Time, timeSamples, 2); 

        // fake up a Field
        FieldImpl displayField = new FieldImpl(animatedFuncType, timeSet);

        // add the first layer to the time stream

        double timeSample1[] = { (double) timeSamples[0][0] };
        double timeSample2[] = { (double) timeSamples[0][1] };
        RealTuple time1 = new RealTuple(timeTupleType, timeSample1);
        RealTuple time2 = new RealTuple(timeTupleType, timeSample2);

        displayField.setSample(time1, displayField1);
        displayField.setSample(time2, displayField2);

        // check the function type

        FunctionType seqType = (FunctionType) displayField.getType();
        RealTupleType testDomainType = seqType.getDomain();
        RealType indexType = (RealType) testDomainType.getComponent(0);

        Set domainSet = (Gridded1DSet) displayField.getDomainSet();

        // create the display and the scales
        DisplayImplJ2D display = new DisplayImplJ2D("myDisplay");
GraphicsModeControl dispGMC = (GraphicsModeControl) display.getGraphicsModeControl(); 
        dispGMC.setScaleEnable(true);
AnimationControl animC = new AnimationControlJ2D(display, time); 
        animC.setOn(true);
        //animC.setStep(1);
        animC.setDirection(true);
ScalarMap colMap = new ScalarMap( domainComponents[1], Display.XAxis ); ScalarMap rowMap = new ScalarMap( domainComponents[0], Display.YAxis ); 
        ScalarMap pixMap = new ScalarMap( rangeType,  Display.RGB );
        ScalarMap animMap = new ScalarMap( indexType , Display.Animation);

        // Add maps to display

        display.addMap( colMap );
        display.addMap( rowMap );
        display.addMap( pixMap );
        display.addMap( animMap );

        // create data reference

        DataReferenceImpl dataReference = new DataReferenceImpl("displayRef");
        dataReference.setData(displayField);

        // add reference to display
        display.addReference( dataReference);

        return display;
    }