Data set must be an array at gnuplot.cgi line 9

##</code><code>##

  use Chart::Graph::Gnuplot qw(gnuplot);
  gnuplot({"title" => "foo",
           "x2-axis label" => "bar",
           "logscale x2" => "1",
           "logscale y" => "1",
           "output type" => "png",
           "output file" => "gnuplot1.png",
           "xtics" => [ ["small\\nfoo", 10], ["medium\\nfoo", 20], ["large\\nfoo", 30] ],
           "ytics" => [10,20,30,40,50]},
           "xdata" => "time",
           "format" => ["x", "%m/%d"],
           "timefmt"=> $date_format,
           "extra_opts" => "set key left top Left",
          [{"title" => "data1",
            "type" => "matrix"}, [[1, 10],
                                  [2, 20],
                                  [3, 30]] ],
          [{"title" => "data2",
            "style" => "lines",
            "type" => "columns"}, [8, 26, 50, 60, 70],
                                  [5, 28, 50, 60, 70] ],
          [{"title" => "data3",
            "style" => "lines",
            "type" => "file"}, "samplefile"],);