Credit Card Validator control for ASP.NET

namespace DataCashTest {
	using System;
	using System.Collections;
	using System.Data;
	using System.Web.UI;
	using System.Web.UI.WebControls;
	using System.IO;
	using System.Text;
	using System.Security;
	using System.Security.Cryptography;

	public class MainPage : Page
	{
	
		protected TextBox CardNumber, StartDate, ExpiryDate, Issue, Amount;
		protected Label Result;
		protected Button ChargeCard;

		protected override void OnLoad(EventArgs e)
		{
			// Add event handler for the click on the button
			ChargeCard.Click += new System.EventHandler(this.ChargeCardOnClick);
			
			base.OnLoad(e);

			// Build the text boxes, provided nobody's clicked the button. If they have
			// then ViewState takes care of retaining the contents.
			if (!IsPostBack) {
				//Nothing to do
			}        
		}
		
		protected void ChargeCardOnClick(Object sender, EventArgs e)
		{
		
			if (IsValid)
			{
				// This is where the normal transaction processing would occur
			}
		}
	}
}