chart not reloading

[KapitanPL]

Hi guys, need help.

  Widget getChart() {
    updateDataCache();
    var colorList = getColorList();
    return isChartEmpty()
        ? const Text("No data to display")
        : Chart(
            data: dataCache,
            variables: {
              'date': Variable(
                accessor: (dynamic datum) => (datum as DataCacheEntry).time,
              ),
              'value': Variable(
                accessor: (dynamic datum) => (datum as DataCacheEntry).value,
              ),
              'group': Variable(
                accessor: (dynamic datum) => (datum as DataCacheEntry).datakey,
              ),
            },
            elements: [
              LineElement(
                position: Varset('date') * Varset('value') / Varset('group'),
                color: colorList.length == 1
                    ? ColorAttr(value: colorList[0])
                    : ColorAttr(
                        variable: 'group',
                        values: getColorList(),
                      ),
              ),
              PointElement(
                position: Varset('date') * Varset('value') / Varset('group'),
                size: SizeAttr(value: 20),
                color: colorList.length == 1
                    ? ColorAttr(value: colorList[0])
                    : ColorAttr(
                        variable: 'group',
                        values: getColorList(),
                      ),
                shape: ShapeAttr(value: CircleShape(hollow: false)),
              )
            ],
            axes: [
              Defaults.horizontalAxis,
              Defaults.verticalAxis,
            ],
          );
  }

this is how I build the chart.
It works while loading data.
Then I change the data.
updateDataCache() changes the data. (Result is what I expect e.g. I change y coordinate of one data point.)
But the chart does not redraw.

What might be a cause?