Type Coercion failed: YahooMap to mx.core.IUIComponent.

TypeError: Error #1034: Type Coercion failed: cannot convert com.yahoo.maps.api::YahooMap@3c466d1 to mx.core.IUIComponent.
at mx.core::Container/http://www.adobe.com/2006/flex/mx/internal::addingChild()[C:\autobuild\3.2.0\frameworks\projects\framework\src\mx\core\Container.as:3259]
at mx.core::Container/addChildAt()[C:\autobuild\3.2.0\frameworks\projects\framework\src\mx\core\Container.as:2207]
at mx.core::Container/addChild()[C:\autobuild\3.2.0\frameworks\projects\framework\src\mx\core\Container.as:2140]
at org.flex.components::YahooMapView/createChildren()[C:\dev\eclipseFlexBuilder\workspaces\dock\flexwork\src\org\flex\components\YahooMapView.as:56]
at mx.core::UIComponent/initialize()[C:\autobuild\3.2.0\frameworks\projects\framework\src\mx\core\UIComponent.as:5370]
at mx.core::Container/initialize()[C:\autobuild\3.2.0\frameworks\projects\framework\src\mx\core\Container.as:2526]
at mx.core::UIComponent/http://www.adobe.com/2006/flex/mx/internal::childAdded()[C:\autobuild\3.2.0\frameworks\projects\framework\src\mx\core\UIComponent.as:5267]
at mx.core::Container/http://www.adobe.com/2006/flex/mx/internal::childAdded()[C:\autobuild\3.2.0\frameworks\projects\framework\src\mx\core\Container.as:3305]
at mx.core::Container/addChildAt()[C:\autobuild\3.2.0\frameworks\projects\framework\src\mx\core\Container.as:2217]
at mx.core::Container/addChild()[C:\autobuild\3.2.0\frameworks\projects\framework\src\mx\core\Container.as:2140]
at org.flex.dock.components::PerspectiveWindow/buildPerspective()[C:\dev\eclipseFlexBuilder\workspaces\dock\flexwork\src\org\flex\dock\components\PerspectiveWindow.as:420]
at org.flex.dock.components::PerspectiveWindow/buildPerspective()[C:\dev\eclipseFlexBuilder\workspaces\dock\flexwork\src\org\flex\dock\components\PerspectiveWindow.as:419]
at org.flex.dock.components::PerspectiveWindow/buildPerspective()[C:\dev\eclipseFlexBuilder\workspaces\dock\flexwork\src\org\flex\dock\components\PerspectiveWindow.as:419]
at org.flex.dock.components::PerspectiveWindow/buildPerspective()[C:\dev\eclipseFlexBuilder\workspaces\dock\flexwork\src\org\flex\dock\components\PerspectiveWindow.as:419]
at org.flex.dock.components::PerspectiveWindow/buildPerspective()[C:\dev\eclipseFlexBuilder\workspaces\dock\flexwork\src\org\flex\dock\components\PerspectiveWindow.as:419]
at org.flex.dock.components::PerspectiveWindow/openPerspective()[C:\dev\eclipseFlexBuilder\workspaces\dock\flexwork\src\org\flex\dock\components\PerspectiveWindow.as:359]
at MainWindow/creationComplete()[C:\dev\eclipseFlexBuilder\workspaces\dock\flexwork\src\MainWindow.mxml:45]
at MainWindow/___MainWindow_BoxModule1_creationComplete()[C:\dev\eclipseFlexBuilder\workspaces\dock\flexwork\src\MainWindow.mxml:6]
at flash.events::EventDispatcher/dispatchEventFunction()
at flash.events::EventDispatcher/dispatchEvent()
at mx.core::UIComponent/dispatchEvent()[C:\autobuild\3.2.0\frameworks\projects\framework\src\mx\core\UIComponent.as:9298]
at mx.core::UIComponent/set initialized()[C:\autobuild\3.2.0\frameworks\projects\framework\src\mx\core\UIComponent.as:1169]
at mx.managers::LayoutManager/doPhasedInstantiation()[C:\autobuild\3.2.0\frameworks\projects\framework\src\mx\managers\LayoutManager.as:718]
at Function/http://adobe.com/AS3/2006/builtin::apply()
at mx.core::UIComponent/callLaterDispatcher2()[C:\autobuild\3.2.0\frameworks\projects\framework\src\mx\core\UIComponent.as:8628]
at mx.core::UIComponent/callLaterDispatcher()[C:\autobuild\3.2.0\frameworks\projects\framework\src\mx\core\UIComponent.as:8568]