RTE on RTE

<?xml version="1.0" encoding="utf-8"?>
<s:WindowedApplication xmlns:fx="http://ns.adobe.com/mxml/2009" 
					   xmlns:s="library://ns.adobe.com/flex/spark" 
					   xmlns:mx="library://ns.adobe.com/flex/mx"
					   xmlns:ns="http://flex.apache.org/experimental/ns"
					   >
	
	<ns:RichTextEditor verticalCenter="0" horizontalCenter="0" width="300" height="300"/>
	
</s:WindowedApplication>

TypeError: Error #1034: Type Coercion failed: cannot convert flash.events::Event@25e81737bbc9 to mx.events.FlexEvent.
at flash.events::EventDispatcher/dispatchEventFunction()
at flash.events::EventDispatcher/dispatchEvent()
at mx.core::UIComponent/dispatchEvent()[/Users/jm/Documents/ApacheFlex4.15/frameworks/projects/framework/src/mx/core/UIComponent.as:13688]
at spark.components::ButtonBarButton/set data()[/Users/jm/Documents/ApacheFlex4.15/frameworks/projects/spark/src/spark/components/ButtonBarButton.as:194]
at spark.components::SkinnableDataContainer/updateRenderer()[/Users/jm/Documents/ApacheFlex4.15/frameworks/projects/spark/src/spark/components/SkinnableDataContainer.as:614]
at spark.components.supportClasses::ListBase/updateRenderer()[/Users/jm/Documents/ApacheFlex4.15/frameworks/projects/spark/src/spark/components/supportClasses/ListBase.as:1248]
at spark.components.supportClasses::ButtonBarBase/updateRenderer()[/Users/jm/Documents/ApacheFlex4.15/frameworks/projects/spark/src/spark/components/supportClasses/ButtonBarBase.as:508]
at spark.components::DataGroup/setUpItemRenderer()[/Users/jm/Documents/ApacheFlex4.15/frameworks/projects/spark/src/spark/components/DataGroup.as:1162]
at spark.components::DataGroup/http://www.adobe.com/2006/flex/mx/internal::itemAdded()[/Users/jm/Documents/ApacheFlex4.15/frameworks/projects/spark/src/spark/components/DataGroup.as:1706]
at spark.components::DataGroup/createItemRenderers()[/Users/jm/Documents/ApacheFlex4.15/frameworks/projects/spark/src/spark/components/DataGroup.as:1062]
at spark.components::DataGroup/commitProperties()[/Users/jm/Documents/ApacheFlex4.15/frameworks/projects/spark/src/spark/components/DataGroup.as:1091]
at mx.core::UIComponent/validateProperties()[/Users/jm/Documents/ApacheFlex4.15/frameworks/projects/framework/src/mx/core/UIComponent.as:8751]
at mx.managers::LayoutManager/validateProperties()[/Users/jm/Documents/ApacheFlex4.15/frameworks/projects/framework/src/mx/managers/LayoutManager.as:605]
at mx.managers::LayoutManager/doPhasedInstantiation()[/Users/jm/Documents/ApacheFlex4.15/frameworks/projects/framework/src/mx/managers/LayoutManager.as:791]
at mx.managers::LayoutManager/doPhasedInstantiationCallback()[/Users/jm/Documents/ApacheFlex4.15/frameworks/projects/framework/src/mx/managers/LayoutManager.as:1188]