如何发现内部异常

我下面的发送邮件代码工作不正常。它没有发送任何电子邮件或返回任何错误。我根本没有从下面的代码中得到抛出的异常。我将如何设置以捕捉以下代码中可能发生的常见错误？

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Text; 
using System.IO; 
using System.Net.Mail; 
using System.Net;
namespace DataAccess 
{ 
    public class DLSendMails 
    {
        public string SendCommentMails(String MemberEmail, int
        { 
            try 
            {
                using (SmtpClient client =
                         new SmtpClient("smtpout.secureserver.net"))
                { 
                    client.Credentials =
                     new NetworkCredential("webmaster@mysite.com", "pwd"); 
                    //client.Credentials
                    //         = CredentialCache.DefaultNetworkCredentials;  
                    //client.DeliveryMethod
                    //         = SmtpDeliveryMethod.Network;  
                    string to = MemberEmail; 
                    var mail = new MailMessage(); 
                    mail.From = new MailAddress("webmaster@mysite.com",
                                                "mysite.com"); 
                    mail.To.Add(to);
                    mail.Subject = "New Comment recieved at mysite.com"; 
                    mail.Body = "You can read your comment and access your "
                              + "profile page by using this link.'n"
                              + "http://www.mysite.com/Member.aspx?UserID="
                              + PicID; 
                    mail.IsBodyHtml = true; 
                    client.Send(mail); 
                    return "sent mail";
                }
            } 
            catch (Exception ex) 
            { 
                // exception handling  
                return ex.ToString(); 
            }
        }
    }
}