oracle触发器 条件,oracle触发器问题

CREATE OR REPLACE TRIGGER "SKY_FINANCEACCREDITPAY_INSERT" BEFORE INSERT ON "COMPANY"."SKY_FINANCEACCREDITPAY" REFERENCING OLD AS "OLD" NEW AS "NEW" FOR EACH ROW

declare

-- local variables here

serialno      integer ;

strTableCode  VARCHAR2(20);

strAutoCode   varchar2(20);

strTableName  VARCHAR2(100);

begin

strTableName := 'SKY_FINANCEACCREDITPAY';

if :new.nbtype is not null then

--取得表的类型编号

SELECT TableCode INTO strTableCode FROM SKY_TableInfo WHERE TableName=strTableName;

if strTableCode is not null then

--取得当天最大流水号

select nvl((max(to_number(substr(AutoCode,12,4)))),0) into serialno

from  SKY_FINANCEACCREDITPAY where substr(AutoCode,4,8)=to_char(sysdate,'yyyymmdd');

--流水号加1

serialno:= serialno + 1;

--为插入的记录AutoCode赋值

strAutoCode:=:new.nbtype|| strTableCode ||to_char(sysdate,'yyyymmdd')||LPad(to_char(serialno),4,'0');

:new.AutoCode:=strAutoCode;

INSERT INTO SKY_AutoCodeInfo(TableName,Autocode) VALUES(strTableName,strAutoCode);

end if;

end if;

end SKY_FINANCEACCREDITPAY_insert;

就是这个触发器有时候条件满足也没有执行，这是什么问题