Flex强制类型转换错误

1、错误描写叙述

TypeError: Error #1034: 强制转换类型失败:无法将 HoleDetailInnerClass0@c2cccf1 转换为 mx.controls.listClasses.IListItemRenderer。
	at mx.controls.dataGridClasses::DataGridColumn/http://www.adobe.com/2006/flex/mx/internal::getMeasuringRenderer()[E:\dev\4.0.0\frameworks\projects\framework\src\mx\controls\dataGridClasses\DataGridColumn.as:1892]
	at mx.controls::DataGrid/commitProperties()[E:\dev\4.0.0\frameworks\projects\framework\src\mx\controls\DataGrid.as:1925]
	at mx.core::UIComponent/validateProperties()[E:\dev\4.0.0\frameworks\projects\framework\src\mx\core\UIComponent.as:7772]
	at mx.managers::LayoutManager/validateProperties()[E:\dev\4.0.0\frameworks\projects\framework\src\mx\managers\LayoutManager.as:572]
	at mx.managers::LayoutManager/doPhasedInstantiation()[E:\dev\4.0.0\frameworks\projects\framework\src\mx\managers\LayoutManager.as:700]
	at mx.managers::LayoutManager/doPhasedInstantiationCallback()[E:\dev\4.0.0\frameworks\projects\framework\src\mx\managers\LayoutManager.as:1072]

2、错误原因

3、解决的方法