[Qt Charts] setting gridlinecolor to black still uses the default color

       ValueAxis {
            id: valueAxis
            min: 2000
            max: 2011
            tickCount: 12
            labelFormat: "%.0f"
            gridLineColor: "black"//"#010101"
        }

        ValueAxis {
            id: valueAxisY
            min: 0
            max: 4.0
            labelFormat: "%.0f"
            gridLineColor: "black"//"#010101"
        }