dygraph y2 axis was never shown

I am build a service based list (php and js/jquery) with dygraphs. I need to show always both y-Scala. At the first hand is to show different values in the same diagram, on the other hand I need the exact same length of the widget. But the y2 Scala was never shown. Does anybody know which restriction makes my configuration useless?

However, I configure the series, with or without different mapping to the one or other Scala, or toggle it. I checked out that the legend is not cut the dygraph canvas.

{
  axes: {
  ​​​  x: {
​​​​      axisLabelWidth: 30,
​​​​      dateWindow: ["2022-02-15T03:57:01.473Z", "2022-02-15T12:57:01.473Z"],
​​​​​      drawAxis: true,
​​​​      pixelsPerLabel: 100
​​​    },
    y: {
​​​​      axisLabelWidth: 40,
​​​​      drawAxis: true,
​​​​      gridLinePattern: [2, 2],
​​​​​      independentTicks: true,
​​​​      pixelsPerLabel: 50,
​​​​      valueFormatter:options_arr.axes.y.valueFormatter(y),
​​​​​      valueRange: [-1, 3],
​​​​​      visibility: true
    },
​​​​    y2: {
​​​​      axisLabelWidth: 40,
​​​​      drawAxis: true,
​​​​      gridLinePattern: [4, 4],
​​​​​      independentTicks: true,
​​​​      pixelsPerLabel: 50,
​​​​      valueFormatter:options_arr.axes.y2.valueFormatter(y2),
​​​​​      valueRange: [-1, 3],
      visibility: true
    },
    ​​​​colors: ["#a1467e", "#000000", "#ff972f", "#ff0000", "#0000c0"],
​​​    connectSeparatedPoints: true,
​​    customBars: true,
​​    disableZoom: true,
​​    height: 300,
​​    labels: ["Time", "B", "Q", "R"],
    labelsDiv: div#archive-legend-7.dygraph-legend,
​​    labelsKMB: true,
​​    labelsSeparateLines: true,
​​    labelsShowZeroValues: true,
​​    legend: "always",
​​    legendFormatter:options_arr.legendFormatter(aData),
​​​    plugins: [ canvas_: canvas, direction_: "both" ],
​​​​    relative: false,
​​    series: {
      "B": {
        axis: "y"
​​​​      },
      "Q": {
​​​​        axis: "y"
      },
      ​​​​"R": {
​​​​        axis: "y"
      }
​​​​    },
    stepPlot: true,
​​    strokeWidth: 2,
​​    title: "B2B",
​​    width: 1200,
​​    xlabel: "Time",
​​    y2label: "SW",
​​    ylabel: "Feedback"
 }
​​​```

If anybody has a clue.