BindingValidationError in TabControl

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Silverlight

Hi I am using MVVM pattern in my project and used Tab Control. Tab Items have validation.

<usercontrol>
    <grid x:name="Layout Root" xmlns:x="#unknown">
        <tabcontrol bindingvalditionerror="TabControl_validtion" x:name="TabControl">
            <tabitem>
                <myusercontrol1 datacontext="{Binding}" />
            </tabitem>
            <tabitem>
                <myusercontrol2 datacontext="{Binding}" />
            </tabitem>
            <tabitem>
                <myusercontrol2 datacontext="{Binding}" />
            </tabitem>
        </tabcontrol>
    </grid>
</usercontrol>

private void TabControl_validtion(object sender, ValidationErrorEventArgs e)
      {
          switch (e.Action)
          {
              case ValidationErrorEventAction.Added:
                  if (!Errors.Contains(e.Error))
                  {
                      this.Errors.Add(e.Error);
                  }
                  break;
              case ValidationErrorEventAction.Removed:
                  this.Errors.Remove(e.Error);
                  break;
              default:
                  break;
          }
      }

it's showing only errors for visible(currently opened) TabItem. And i need to show all the errors from all tabs. How can i achieve this?