我正在尝试使用画布叠加在烛台图表上绘制一条水平线，但出现错误：对象不支持属性或方法“series_u2p”错误？
知道可能是什么原因吗？
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<title></title>
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<div id="chart" style="height: 250px; width: 600px;"></div>
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var plot;
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$.jqplot.config.enablePlugins = true;
plot = $.jqplot('chart', [ohlc], {
seriesDefaults: {
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axes: {
xaxis: {
renderer: $.jqplot.DateAxisRenderer,
tickOptions: {
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min: "09-01-2008",
max: "06-22-2009",
tickInterval: "6 weeks",
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y2axis: {
tickOptions: {
formatString: '$%d'
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}
},
series: [{
renderer: $.jqplot.OHLCRenderer,
rendererOptions: {
candleStick: true
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zoom: true,
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ohlc = [
['06/15/2009 16:00:00', 136.01, 139.5, 134.53, 139.48],
['06/08/2009 16:00:00', 143.82, 144.56, 136.04, 136.97],
['06/01/2009 16:00:00', 136.47, 146.4, 136, 144.67],
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['04/27/2009 16:00:00', 122.9, 127.95, 122.66, 127.24],
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['04/13/2009 16:00:00', 120.01, 124.25, 115.76, 123.42],
['04/06/2009 16:00:00', 114.94, 120, 113.28, 119.57],
['03/30/2009 16:00:00', 104.51, 116.13, 102.61, 115.99],
['03/23/2009 16:00:00', 102.71, 109.98, 101.75, 106.85],
['03/16/2009 16:00:00', 96.53, 103.48, 94.18, 101.59],
['03/09/2009 16:00:00', 84.18, 97.2, 82.57, 95.93],
['03/02/2009 16:00:00', 88.12, 92.77, 82.33, 85.3],
['02/23/2009 16:00:00', 91.65, 92.92, 86.51, 89.31],
['02/17/2009 16:00:00', 96.87, 97.04, 89, 91.2],
['02/09/2009 16:00:00', 100, 103, 95.77, 99.16],
['02/02/2009 16:00:00', 89.1, 100, 88.9, 99.72],
['01/26/2009 16:00:00', 88.86, 95, 88.3, 90.13],
['01/20/2009 16:00:00', 81.93, 90, 78.2, 88.36],
['01/12/2009 16:00:00', 90.46, 90.99, 80.05, 82.33],
['01/05/2009 16:00:00', 93.17, 97.17, 90.04, 90.58],
['12/29/2008 16:00:00', 86.52, 91.04, 84.72, 90.75],
['12/22/2008 16:00:00', 90.02, 90.03, 84.55, 85.81],
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['11/10/2008 16:00:00', 100.17, 100.4, 86.02, 90.24],
['11/03/2008 16:00:00', 105.93, 111.79, 95.72, 98.24],
['10/27/2008 16:00:00', 95.07, 112.19, 91.86, 107.59],
['10/20/2008 16:00:00', 99.78, 101.25, 90.11, 96.38],
['10/13/2008 16:00:00', 104.55, 116.4, 85.89, 97.4],
['10/06/2008 16:00:00', 91.96, 101.5, 85, 96.8],
['09/29/2008 16:00:00', 119.62, 119.68, 94.65, 97.07],
['09/22/2008 16:00:00', 139.94, 140.25, 123, 128.24],
['09/15/2008 16:00:00', 142.03, 147.69, 120.68, 140.91]
];
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<script type="text/javascript">
function lineup() {
var co = plot.plugins.canvasOverlay;
var line = co.get('lineOne');
line.options.y += 1;
co.draw(plot);
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