oracle触发器中，为什么在这段代码会报异常呢？。。。。。。。。。。。。。。。

我要问的问题，写在下面的触发器里了，请大家多多指教
create or replace trigger tg_kfs_res
  after insert on t_kfsample
  for each row
declare
   v_asy_time date;
   v_goodorbad number;
   v_fe2o3 number;
   v_sio2 number;
   v_al2o3 number;
   v_cao number;
   v_mgo number;
   v_na2o number;
   v_k2o number;
   v_s number;
   v_p number;
   v_as number;
   v_b number;
   v_cr number;
   v_cu number;
   v_ni number;
   v_mo number;
   v_co number;
   v_v number;
   v_sn number;
   v_ba number;
   v_hg number;
   v_count number;
   v_delegate varchar2(9); --委托快分码
   v_s_fe2o3 number;
   v_s_sio2 number;
   v_s_al2o3 number;
   v_s_cao number;
   v_s_mgo number;
   v_s_na2o number;
   v_s_k2o number;
   v_s_s number;
   v_s_p number;
   v_s_as number;
   v_s_b number;
   v_s_cr number;
   v_s_cu number;
   v_s_ni number;
   v_s_mo number;
   v_s_co number;
   v_s_v number;
   v_s_sn number;
   v_s_ba number;
   v_s_hg number;
   v_s_count number;
   v_s_asy_time date;
   v_s_goodorbad number;
   v_sample_id varchar2(11);
   v_seq varchar2(2);
   v_num number;
   --myexception exception;
   v_s_id varchar2(12);
begin
--首先取出t_kfsample表中的记录
    v_s_id :=:new.fd_sample_id;
--为什么执行下面这个查询语句就跑到exception那个地方去了呢，v_s_id 是有值的，而且根据这个v_s_id也是可以查到数据的 ，但是为什么会跳到异常里了呢？请教大家
    select count(*) into v_count from t_kfsample where fd_sample_id=v_s_id;
    if(v_count>0) then
          select fd_analy_time,fd_goodorbad ,fd_Fe2O3,fd_SiO2,fd_Al2O3,
          fd_CaO,fd_MgO,fd_Na2O,fd_K2O,fd_S,fd_P,fd_As,fd_B,fd_Cr,
          fd_Cu,fd_Ni,fd_Mo,fd_Co,fd_V,fd_Sn,fd_Ba,fd_Hg,fd_sample_id
          into v_asy_time, v_goodorbad,v_fe2o3,v_sio2,v_al2o3,
                v_cao,v_mgo ,v_na2o,v_k2o ,v_s , v_p, v_as,
                v_b,v_cr,v_cu,v_ni,v_mo,v_co,v_v,v_sn,
                v_ba,v_hg, v_delegate
          from t_kfsample where FD_SAMPLE_ID=v_s_id;
          if v_delegate is not null then
                --取出t_sample 表中的记录
              select count(*) into v_s_count from t_sample where fd_delegate=v_delegate;
              if(v_s_count>0) then
                    select fd_sample_id,fd_analy_time,fd_goodorbad ,fd_Fe2O3,fd_SiO2,fd_Al2O3,
                        fd_CaO,fd_MgO,fd_Na2O,fd_K2O,fd_S,fd_P,fd_As,fd_B,fd_Cr,
                        fd_Cu,fd_Ni,fd_Mo,fd_Co,fd_V,fd_Sn,fd_Ba,fd_Hg,fd_seq
                        into v_sample_id,v_s_asy_time, v_s_goodorbad,v_s_fe2o3,v_s_sio2,v_s_al2o3,
                        v_s_cao,v_s_mgo ,v_s_na2o,v_s_k2o ,v_s_s , v_s_p, v_s_as,
                        v_s_b,v_s_cr,v_s_cu,v_s_ni,v_s_mo,v_s_co,v_s_v,v_s_sn,
                        v_s_ba,v_s_hg,v_seq  from t_sample where fd_delegate=v_delegate;
                  end if;
           end if;
      else
          dbms_output.put_line('没有找到该记录');
      end if;
      if v_delegate is not null then
         v_num:=0;
         select count(*)into v_num from t_send_buff where fd_sample_id=v_sample_id and fd_delegate=v_delegate;
         if v_num<=0 then
               insert into t_send_buff(fd_sample_id,fd_message_id, fd_delegate,fd_seq)
               values(v_sample_id,'1B0F52',v_delegate,v_seq);
               insert into t_send_buff(fd_sample_id,fd_message_id,fd_delegate,fd_seq)
               values(v_sample_id,'1B0H51',v_delegate,v_seq);
                        
                  
         end if;
      end if;
     commit ;
  exception
       when others then
        dbms_output.put_line('错误信息为:'|| sqlcode || ':' || sqlerrm);
       
end tg_kfsample_insert;