1。

var log = (from s in dx.s_events
                 where s.e_id == st
                 select new { s }).FirstOrDefault();

可能没有针对您身份的任何记录。



2.

there might not be any record available against the id you've.

2.

int st = Convert.ToInt16((Request.QueryString["e_id"]));

检查您是否在此处收到有效值。

3.

Check if you are receiving valid values here.
3.

mail.Body = log.s.e_name;

检查log.s是否为空。

Check if "log.s" is not null.