Working with container in flex 3.0

hi,

i am using adobe flex 3.0 for my designs.
i am working on using drag and drop containers.
while working with containers i drag and drop the container box, its works good.
the code is:
-----------------------------------------
<containersDnDContainer width="100%" height="200" horizontalAlign="center" verticalAlign="middle" paddingTop="10" verticalGap="10"
direction="horizontal" borderStyle="solid" id="right" backgroundColor="blue" backgroundAlpha=".25">
<mx:Box backgroundColor="yellow" width="150" height="150" mouseDown="DnDManager.getInstance().doDrag(event)"/>

<mx:Box backgroundColor="green" width="150" height="150" mouseDown="DnDManager.getInstance().doDrag(event)"/>
<mx:Box backgroundColor="purple" width="150" height="150" mouseDown="DnDManager.getInstance().doDrag(event)"/>
</containersDnDContainer>
-------------------------------------------

now i am trying to place a data grid in the container box. i need the functionality like the container box i.e. if i drag the datagrid it must move to another place.
i gave datagrid clolumn property as "dragable columns" as "false". and use the code is:
---------------------------------------
<containersDnDContainer width="100%" height="200" horizontalAlign="center" verticalAlign="middle" paddingTop="10" verticalGap="10"
direction="horizontal" borderStyle="solid" id="bottom" backgroundColor="blue" backgroundAlpha=".25">
<mx:Box width="150" height="150" mouseDown="DnDManager.getInstance().doDrag(event)" >
<mxataGrid x="10" y="20" width="213" mouseDown="DnDManager.getInstance().doDrag(event)" draggableColumns="false">
<mx:columns>
<mxDataGridColumn headerText="Address" dataField="Address"/>
<mxDataGridColumn headerText="City" dataField="City"/>
<mxDataGridColumn headerText="Country" dataField="Country"/>
</mx:columns>
</mxDataGrid>
</mx:Box>
</containersDnDContainer>
--------------------------------------
but it gave the error like this:

Error #1034: Type Coercion failed: cannot convert mx.controls:ataGrid@9d4c0a1 to dNdLib.containers.IDnDContainer. at dNdLib.managers:nDManager/doDrag()


will you please reply me with solution.



thank u....

with best regards...
srikanth