public class MyClass

    {

        public int StartValue { get; set; }

        public int EndValue { get; set; }

    }

 public class RangeValidationRule : ValidationRule

    {

        public override ValidationResult Validate(object value, CultureInfo cultureInfo)

        {

            BindingGroup bindingGroup = (BindingGroup)value;

            MyClass mc = (MyClass)bindingGroup.Items[0];

            int startValue = (int)bindingGroup.GetValue(mc, "StartValue");

            int endValue = (int)bindingGroup.GetValue(mc, "EndValue");

            bool isEnabled = (bool)bindingGroup.GetValue(mc, "IsEnabled");

            if (startValue > endValue)

            {

                return new ValidationResult(true, null);

            }

            return new ValidationResult(false, "Input should between 0 and 100");

        }

    }

 MyClass mc = new MyClass();

        public MainWindow()

        {

            InitializeComponent();

            this.DataContext = mc;

        }

 <Grid Name="Grid1" Width="400" Height="300" >

        <Grid.RowDefinitions>

            <RowDefinition/>

            <RowDefinition/>

            <RowDefinition/>

        </Grid.RowDefinitions>

        <Grid.BindingGroup>

            <BindingGroup NotifyOnValidationError="True">

                <BindingGroup.ValidationRules >

                    <local:RangeValidationRule2 ValidationStep="ConvertedProposedValue"  />

                </BindingGroup.ValidationRules>

            </BindingGroup>

        </Grid.BindingGroup>

        <TextBox Grid.Row="0" Name="tb1" Text="{Binding StartValue}">

        </TextBox>

        <TextBox Grid.Row="1" Text="{Binding EndValue}"/>

        <Button Name="btn1" Content="btn1" Grid.Row="2" Click="Button_Click"  >

        </Button>

    </Grid>

  this.Grid1.BindingGroup.CommitEdit();