The wjFlexChartAnnotation must be contained in a wjFlexChartAnnotationLayer binding.For example:

<p>Here is a AnnotationLayer:</p>
<div data-bind="wjFinancialChart: { itemsSource: fData, bindingX: 'date', chartType:'Candlestick' }">
   <div data-bind="wjFinancialChartSeries: { bindingX: 'date', binding: 'high,low,open,close' }"></div>
   <div data-bind="wjFlexChartAnnotationLayer: {}">
       <div data-bind="wjFlexChartAnnotation: { type: 'Rectangle', content: 'E',height:20, width:20,attachment:'DataIndex',pointIndex: 10}"></div>
       <div data-bind="wjFlexChartAnnotation: { type: 'Ellipse', content: 'E',height:20, width:20,attachment:'DataIndex',pointIndex: 30}"></div>
   </div>
</div>

The wjFlexChartAnnotation is used to represent all types of possible annotation shapes like Circle, Rectangle, Polygon and so on. The type of annotation shape is specified in the type attribute.