I can't get my axes to display using isFloatingAxis in core-plot

Question

I'm using core-plot to display data that doesn't pass through zero on x or y axes, and I'd like the axes to be displayed too. The data is displayed correctly but the axes aren't shown at all. I see that the API has changed recently and it appears that the property to use is isFloatingAxis but I still can't get it to display. My code is below, based on the tutorial on switchonthecode.com:

    graph = [[CPXYGraph alloc] initWithFrame:self.view.bounds];
 CPLayerHostingView *hostingView = (CPLayerHostingView *) self.view;
 hostingView.hostedLayer = graph;
 graph.paddingLeft = 20.0;
 graph.paddingTop = 20.0;
 graph.paddingRight = 20.0;
 graph.paddingBottom = 20.0;

 CPXYPlotSpace *plotSpace = (CPXYPlotSpace *)graph.defaultPlotSpace;
 double minTime = [tideLocation minTime];
 double maxTime = [tideLocation maxTime];
 double range = maxTime - minTime;

 float minHeight = [tideLocation minHeight];
 float maxHeight = [tideLocation maxHeight];
 float range2 = maxHeight - minHeight;

 plotSpace.xRange = [CPPlotRange plotRangeWithLocation:CPDecimalFromDouble(minTime)
               length:CPDecimalFromDouble(range)];
 plotSpace.yRange = [CPPlotRange plotRangeWithLocation:CPDecimalFromFloat(minHeight) 
               length:CPDecimalFromFloat(range2)];

 CPLineStyle *lineStyle = [CPLineStyle lineStyle];
 lineStyle.lineColor = [CPColor blackColor];
 lineStyle.lineWidth = 2.0f;

 CPXYAxisSet *axisSet = (CPXYAxisSet *)graph.axisSet;
 CPConstraints xConstraints = {CPConstraintNone};

 axisSet.xAxis.majorIntervalLength = [[NSDecimalNumber decimalNumberWithString:@"3600"] decimalValue];
 axisSet.xAxis.minorTicksPerInterval = 4;
 axisSet.xAxis.majorTickLineStyle = lineStyle;
 axisSet.xAxis.minorTickLineStyle = lineStyle;
 axisSet.xAxis.axisLineStyle = lineStyle;
 axisSet.xAxis.minorTickLength = 5.0f;
 axisSet.xAxis.majorTickLength = 7.0f;
 //axisSet.xAxis.axisLabelOffset = 3.0f;
 axisSet.xAxis.constraints = xConstraints;
 axisSet.xAxis.isFloatingAxis = YES;

 axisSet.yAxis.majorIntervalLength = [[NSDecimalNumber decimalNumberWithString:@"5"] decimalValue];
 axisSet.yAxis.minorTicksPerInterval = 4;
 axisSet.yAxis.majorTickLineStyle = lineStyle;
 axisSet.yAxis.minorTickLineStyle = lineStyle;
 axisSet.yAxis.axisLineStyle = lineStyle;
 axisSet.yAxis.minorTickLength = 5.0f;
 axisSet.yAxis.majorTickLength = 7.0f;
 //axisSet.yAxis.axisLabelOffset = 3.0f;
 axisSet.yAxis.constraints = xConstraints;
 axisSet.yAxis.isFloatingAxis = YES;

 CPScatterPlot *tidePlot = [[[CPScatterPlot alloc]
         initWithFrame:CGRectMake(90, 12, 200, 25)] autorelease];
 tidePlot.identifier = @"Tide Plot";
 tidePlot.dataLineStyle.lineWidth = 1.0f;
 tidePlot.dataLineStyle.lineColor = [CPColor redColor];
 tidePlot.dataSource = self;
 [graph addPlot:tidePlot];