QML LineSeries - ChartView

[neda]

Hi,
I have a "chartview" with 3 LineSeries.
I try to use "xAxisSeries" and "yAxisSeries" to specifying Axis.

ValueAxis {
                    id: axisY
                    min: chartHelper.yMin 
                    max: chartHelper.yMax                    
                    tickInterval: chartHelper.tickIntervalAxisY                   
                }
                ValueAxis {
                    id: axisX
                    min: chartHelper.xMin 
                    max: chartHelper.xMax                    
                    tickInterval:chartHelper.tickIntervalAxisX
                }

                LineSeries {
                    id: orginalChartLineSeries                    
                    axisX: axisX
                    axisY: axisY
                    useOpenGL:true                    
                    pointsVisible: false
                    pointLabelsVisible: true
                }

                LineSeries {
                    id:xAxisSeries
                    XYPoint { x: chartHelper.xMin; y: 0 }
                    XYPoint { x: chartHelper.xMax; y: 0 }
                    color: "Black"
                    width: 2
                     axisX: axisX
                     axisY: axisY
                }
                LineSeries {
                    id:yAxisSeries
                    XYPoint { x: 0; y: chartHelper.yMin }
                    XYPoint { x: 0; y: chartHelper.yMax }
                    color: "Black"
                    width: 2
                }

But I don't see "xAxisSeries" and "yAxisSeries" (just see "orginalChartLineSeries").
I have to use the below code:

xAxisSeries.append(chartHelper.xMin,0);
 xAxisSeries.append(chartHelper.xMax,0);
yAxisSeries.append(0,chartHelper.yMin);
yAxisSeries.append(0,chartHelper.yMax);

The above code is well and everything is ok but I don't like to use this code because I have used "XYPoint".