ASP.NET Custom Error Page

Hi all,
I created custom error page on my site, which whenever an exception raises in the site, an error message will be displayed to the customers and in background an email with full details of the error will be going to the adminstrator.
i can see the custom error page but,i cannot see any error on tht page(i'm getting NULLEXCEPTION)
here is my custom error page code (ApplicationError.aspx.cs)
protected void Page_Load(object sender, EventArgs e) { Exception CurrentException = Server.GetLastError().GetBaseException(); string ErrorDetails = CurrentException.ToString(); // Send notification e-mail MailMessage Email =new MailMessage("xyz@gmail.com", "abc@veeturiconsulting.com"); Email.IsBodyHtml = false; Email.Subject = "WebSite Access ERROR!"; Email.Body = ErrorDetails; Email.Prio ...