[输入输出] FORTRAN中WRITE不执行？

PROGRAM TEST

!IN THE MAIN BODY

IOUTFILE=100
IOUTFIEL1=101

OPEN (IOUTFILE,'FILE NAME')

OPEN(IOUTFILE1,'FILE NAME')

CALL PRNT()

! THE MAIN BODY IGNORED FOR THIS MOMENT……


STOP
END PROGRAM

SUBROUTINE PRNT(IOUFILE,IOUTFILE1)

DO I=1,N
WRITE(IOUTFILE,'FORMAT') SOME FACTORS.....
ENDDO

!THE PREVIOUS PART WORK NORMALLY

WRITE(IOUTFILE1,*) SOME FACTOR  !THE ERROR

!THIS 'WRITE' DOESN'T WORK, WHY?


RETURN 
END 

AND THE FUNNY THING IS, IF THE PROGRAM WORK PERFECTLY, THE "WRITE" COULD BE EXCUTED..

PROGRAM TEST
  Implicit None
  integer :: IOUTFILE , IOUTFILE1
!IN THE MAIN BODY

IOUTFILE=100
IOUTFILE1=101

OPEN(IOUTFILE,File='file1.txt')

OPEN(IOUTFILE1,File='file2.txt')

CALL PRNT(IOUTFILE,IOUTFILE1)

! THE MAIN BODY IGNORED FOR THIS MOMENT……


STOP
END PROGRAM

SUBROUTINE PRNT(IOUTFILE,IOUTFILE1)
  Implicit None
  integer :: IOUTFILE , IOUTFILE1
  Integer :: n , i
  n = 3
DO I=1,N
WRITE(IOUTFILE,*) 's'
ENDDO

!THE PREVIOUS PART WORK NORMALLY

WRITE(IOUTFILE1,*) 'vs'!SOME FACTOR  !THE ERROR

!THIS 'WRITE' DOESN'T WORK, WHY?


RETURN 
END 

!AND THE FUNNY THING IS, IF THE PROGRAM WORK PERFECTLY, THE "WRITE" COULD BE EXCUTED..