PLS-00905: 对象MANAGER.LETER_MES 无效，这个错误如何解决啊

TRIGGER MANAGER.LETER_DATA 编译错误
错误：PLS-00905: 对象 MANAGER.LETER_MES 无效
这个错误如何解决啊

create or replace procedure leter_mes(number_borrowing VARCHAR2)
as
begin
    select target_date into t_date from  book_borrowing_and_returning = number_borrowing;
    select return_date into r_date from  book_borrowing_and_returning = number_borrowing;
    select rea_cno into cno_1 from  ticket;
    select borrowing_number into bor_num from  penalty_information;
    select name into nam_1 from  readers  where cno= (select rea_cno from Book_borrowing_and_returning);
    num_1 := r_date - t_date;
    if t_date < r_date then
      insert into ticket values('8008800810001',cno_1,bor_num,num_1,nam_1);
    end if;
end;
  
CREATE OR REPLACE TRIGGER leter_data
after insert or delete or update of return_date
on book_borrowing_and_returning
for each row
declare
  PRAGMA AUTONOMOUS_TRANSACTION;
  cno_1  VARCHAR2(13);
  bor_num     VARCHAR2(13);
  nam_1 VARCHAR2(8);
  t_date date;
  r_date date;
  num_1 number(8,2);  
  number_borrowing VARCHAR2(13);
begin
    leter_mes(number_borrowing);
end;

用PLSQL Developer打开这个存储过程 MANAGER.LETER_MES ，下面会显示这个对象为什么无效，根据提示把这个存储过程改对即可