HELP : cobol中的REWRITE

a01

我用I-O打开一个顺序文件, 读取第一条记录后, 要更新它,
但总是说:记录的长度非法.
但两条记录的长度都是一样的. 不知为什么?
信息如下:
Message . . . . :   I/O operation failed in program ABC in XXXXX (C D F  
  G).                                                                          
Cause . . . . . :   Program ABC in QTEMP issued an I/O operation on file
  ABCD at COBOL statement 2308 which failed with file status 44; and no      
  error handler existed. When an unsuccessful file status is received from an  
  I/O operation, an AT END/INVALID KEY, USE PROCEDURE, or FILE STATUS should   
  be coded to handle the error.