have you tried.
Is the validateNow() method called on the datagrid itself or the underlying arraycollection dataprovider?
This is kind of hard to debug without seeing the code. But i would try the
That should get you what you want.
You also might want to try myDataProvider.refresh(), where myDataProvider is the data provider for the DataGrid. Make sure you are using a collection like ArrayCollection or XMLListCollection and you are using the [Bindable] metadata tag.
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