Column ChartShows Image when Data Meets Certain Conditions

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A column chart displays vertical bars with the values axis being displayed on the left (or right) side of the chart. To create a column chart, the <Column2DChart> (or <Column3DChart>) and <Column2DSeries> (or <Column3DSeries>) elements must be set in Layout. The yField attribute on the <Column2DSeries> element must be set to the field name where the data value exists, as the size of the data is displayed on the vertical axis (Y-axis).
<Column2DSeries yField="Vancouver" labelPosition="inside" displayName="Vancouver" color="#ffffff" >

var chartData = [
{"Month":"Mar","Vancouver":28.8},
{"Month":"Apr","Vancouver":35.8},
{"Month":"May","Vancouver":47.6},
{"Month":"Jun","Vancouver":74.2},
{"Month":"Jul","Vancouver":60.1},
{"Month":"Aug","Vancouver":44.2},
{"Month":"Sep","Vancouver":34.2}
];
In this example, one <Column2DSeries> element is defined, and it draws a horizontal line at the point corresponding to Y-axis value 70.
<Column2DChart showDataTips="true" columnWidthRatio="0.46">
...
<series>
<Column2DSeries yField="Data" htmlJsFunction="userFunction">
...
</Column2DSeries>
</series>
...
<annotationElements>
<AxisMarker fontSize="15">
<lines>
<AxisLine value="70" label="Target" fontFamily="Malgun Gothic">
<stroke>
<Stroke color="#ef562d" weight="2"/>
</stroke>
</AxisLine>
</lines>
</AxisMarker>
</annotationElements>
</Column2DChart>