使用DataGridTextColumn验证禁用/启用按钮

I have this DataGrid:

我有这个DataGrid:

<DataGrid ItemsSource="{Binding CustomerXml}" 
     Name="customersDataGrid" AutoGenerateColumns="False" DataContext="{Binding}">
     <DataGrid.Columns>
         <DataGridTextColumn Header="Name">
             <DataGridTextColumn.Binding>
                 <Binding Path="Name" ValidatesOnDataErrors="True" 
                     UpdateSourceTrigger="PropertyChanged" NotifyOnValidationError="True">
                     <Binding.ValidationRules>
                         <local:NameValidationRule/>
                     </Binding.ValidationRules>
                 </Binding>
             </DataGridTextColumn.Binding>
         </DataGridTextColumn>

         ...

     </DataGrid.Columns>          
 </DataGrid>
<DataGr