How to validate a cell within a DataGridView Row When it's Skipped

hi
i help you

but i am not good in english if you don't understand pls tell me

now

look i have datagridview with one cell
But the data must be in this cell conditions
"The name of the customer may contain only Latin letters and empty spaces and must start with a letter."

code Xaml this: but oops i use telerik sory...

<telerik:RadGridView  CellValidating="RadGridView1_CellValidating" Name="RadGridView1" CanUserFreezeColumns="False" ItemsSource="{Binding Customers}" AutoGenerateColumns="False" ActionOnLostFocus="CommitEdit"
                             RowIndicatorVisibility="Visible">
            <telerik:RadGridView.Columns>
                <telerik:GridViewDataColumn DataMemberBinding="{Binding ContactName}" Header="Contact Name *" />
       </telerik:RadGridView>

and this code CS :

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text.RegularExpressions;
using System.Windows.Controls;
using System.Windows.Media;
using Telerik.Windows.Controls.GridView;
using Telerik.Windows.Controls.GridView.Cells;
using ValidationResult=Telerik.Windows.Controls.GridView.ValidationResult;
using Telerik.Windows.Controls;
namespace GridView.Validation
{
    public partial class Example
    {
        private List<string> allCountries;
        public Example()
        {
            InitializeComponent();
        }


public void RadGridView1_CellValidating(object sender, GridViewCellValidatingEventArgs e)
        {
            bool isValid = true;
            string validationText = "Validation failed. ";
            GridViewCell cell = e.Cell;
                    isValid = ValidateName((string) e.NewValue);
                    if (!isValid)
                    {
                        validationText += "The name of the customer may contain only Latin letters" +
                                          Environment.NewLine + "and empty spaces and must start with a letter.";
                    }
}

private static bool ValidateName(string name)
        {
            if (name == null)
            {
                return false;
            }
            return Regex.IsMatch(name, @"^([A-Za-z]+\s*)+$");
        }

i user Regex ........ but you must put this when you use Regex

using System.Text.RegularExpressions;

end

if i help you pls tell me ....