SL Validation not firing

I am having an issue in my SL app, with mvvm, where validation will not fire back to the UI. I have added the appropriate xaml properties (Mode=TwoWay, ValidatesOnExceptions=True, NotifyOnValidationError=True). When the entity loads it runs the validation but when I change the property it is not verifying again.  Verification works fine in my WPF app built with the same DomainModel. My SL Domain Model links to the files of the DomainModel. In a SL test scenerio I bound directly to an entity property on one field and in another used my DataContext property to assign a value to the  same property. I did find that binding through the mvvm property did not fire validation. I have also found that using your metadata helper classes doesn't do anything in my WPF app or my SL app.

I beleive it was the type of validation I was doing.