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:dev4.0.0frameworksprojectsframeworksrcmxcontrolsdataGridClassesDataGridColumn.as:1892]
	at mx.controls::DataGrid/commitProperties()[E:dev4.0.0frameworksprojectsframeworksrcmxcontrolsDataGrid.as:1925]
	at mx.core::UIComponent/validateProperties()[E:dev4.0.0frameworksprojectsframeworksrcmxcoreUIComponent.as:7772]
	at mx.managers::LayoutManager/validateProperties()[E:dev4.0.0frameworksprojectsframeworksrcmxmanagersLayoutManager.as:572]
	at mx.managers::LayoutManager/doPhasedInstantiation()[E:dev4.0.0frameworksprojectsframeworksrcmxmanagersLayoutManager.as:700]
	at mx.managers::LayoutManager/doPhasedInstantiationCallback()[E:dev4.0.0frameworksprojectsframeworksrcmxmanagersLayoutManager.as:1072]

2、错误原因

3、解决的方法