D3js - TypeError: string undefined

I do not understand this error:

TypeError: string undefined function d3_time_parse (date, template, string, j) {var c, p, i = 0, n = template.length, m = string.length; ...

Here is my code:

    var margin = {top: 20, right: 80, bottom: 30, left: 50},
        width = 960 - margin.left - margin.right,
        height = 500 - margin.top - margin.bottom;

    var parseDate = d3.time.format ("% Y% m% d"). parse;

    var x = d3.time.scale ()
        .range ([0, width]);

    var y = d3.scale.linear ()
        .range ([height, 0]);

    var color = d3.scale.category10 ();

    var xAxis = d3.svg.axis ()
        .scale (x)
        .orient ("bottom");

    var yAxis = d3.svg.axis ()
        .scale (y)
        .orient ("left");

    var line = d3.svg.line ()
        .interpolate ("basis")
        .x (function (d) {return x (d.date);})
        .y (function (d) {return y (d.index);});

    var svg = d3.select ("body"). append ("svg")
        .attr ("width", width + margin.left + margin.right)
        .attr ("height", height + margin.top + margin.bottom)
      .append ("g")
        .attr ("transform", "translate (" + margin.left + "," + margin.top + ")");

    d3.csv ("data.csv", function (error, data) {
      color.domain (d3.keys (data [0]). filter (function (key) {return key! == "date";}));

      data.forEach (function (d) {
        d.date = parseDate (d.date);
      });

      var indexes = color.domain (). map (function (name) {
        return {
          name: name,
          values: data.map (function (d) {
            return {date: d.date, index: + d [name]};
          })
        };
      });

      x.domain (d3.extent (data, function (d) {return d.date;}));

      y.domain ([
        d3.min (indexes, function (c) {return d3.min (c.values, function (v) {return v.index;});}),
        d3.max (indexes, function (c) {return d3.max (c.values, function (v) {return v.index;});})
      ]);

      svg.append ("g")
          .attr ("class", "x axis")
          .attr ("transform", "translate (0," + height + ")")
          .call (xAxis);

      svg.append ("g")
          .attr ("class", "y axis")
          .call (yAxis)
        .append ("text")
          .attr ("transform", "rotate (-90)")
          .attr ("y", 6)
          .attr ("dy", ".71em")
          .style ("text-anchor", "end")
          .text ("Variation (%)");

      var index = svg.selectAll (". index")
          .data (indexes)
        .enter (). append ("g")
          .attr ("class", "index");

      index.append ("path")
          .attr ("class", "line")
          .attr ("d", function (d) {return line (d.values);})
          .style ("stroke", function (d) {return color (d.name);});

      index.append ("text")
          .datum (function (d) {return {name: d.name, value: d.values ​​[d.values.length - 1]};})
          .attr ("transform", function (d) {return "translate (" + x (d.value.date) + "," + y (d.value.index) + ")"}})
          .attr ("x", 3)
          .attr ("dy", ".35em")
          .text (function (d) {return d.name;});
    });

and my csv file looks like this:

Date, DAX, CAC40, FTSE, NASDAQ, Other
20060407, -0.000712859, -0.009013212,0.010819606,0.009846526,0.003082604
20060413, -0.007765968, -0.024263398,0.011238971,0.004128621,0.005952774
20060421,0.02261859,0.00330204,0.028734861,0.001688981,0.003459211
20060428,0.007170521, -0.007531405,0.010534438, -0.002416181,0.004012361
...

Can someone please help me? thanks skeut