发送带附件的邮件失败?

代码如下:public partial class SendMail : System.Web.UI.Page
{
    private string path="";    protected void Page_Load(object sender, EventArgs e)
    {
        path = @"~/attachment.xls";        path = Server.MapPath(path);        bool result = SendEmail(path);        Response.Write(result);
    }
    public static bool SendEmail(string path)
    {
        bool isSend = false;        System.Web.Mail.MailMessage objMailMessage = new System.Web.Mail.MailMessage();        objMailMessage.From = "cs@***.cc";
        
        objMailMessage.Cc = "***@qq.com;**@21cn.com";
        objMailMessage.To = "***@qq.com;**@21cn.com";
        objMailMessage.Subject = "Test mail";
        
        objMailMessage.BodyFormat = MailFormat.Html;
        objMailMessage.Body = "this is test message.";        objMailMessage.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate", "1");
        objMailMessage.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendusername", "****");
        objMailMessage.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendpassword", "****");        SmtpMail.SmtpServer = "mail.***.cc";        if (!string.IsNullOrEmpty(path))
        {
            string[] pathArray = path.Split(',');
            Attachment data;
            ContentDisposition disposition;
            for (int i = 0; i < pathArray.Length; i++)
            {
                data = new Attachment(pathArray[i], MediaTypeNames.Application.Octet);//实例化附件  
                disposition = data.ContentDisposition;
                disposition.CreationDate = System.IO.File.GetCreationTime(pathArray[i]);//获取附件的创建日期  
                disposition.ModificationDate = System.IO.File.GetLastWriteTime(pathArray[i]);//获取附件的修改日期  
                disposition.ReadDate = System.IO.File.GetLastAccessTime(pathArray[i]);//获取附件的读取日期                objMailMessage.Attachments.Add(data);//添加到附件中
            }
        }
        try
        {
            SmtpMail.Send(objMailMessage);
            isSend = true;        }
        catch (Exception e)
        {
            return isSend;
        }        return isSend;
    }
}
提交后..打印出来的result为false..为什么? 如果不带附件path为空的时候..能正常发送..