office2hashcat.py error

I hope it is OK to post on this forum for help with office2hashcat

I am getting the following output when using office2hashcat on a 97-2003 Power Point file.

Traceback (most recent call last):
  File "office2hashcat.py", line 2018, in <module>
    ret = process_file(sys.argv[i].decode("utf8"))
  File "office2hashcat.py", line 1995, in process_file
    find_rc4_passinfo_ppt(filename, sppt, offset)
  File "office2hashcat.py", line 1728, in find_rc4_passinfo_ppt
    persistOffset = unpack("<L", stream.read(4))[0]
struct.error: unpack requires a string argument of length 4

I have used the script on a file that I created and password protected and got the hash no problem.

I would appreciate if someone could point me in the right direction on how I can extract the hash from this file.

Thank you