I cant open a cptx file in Captivate 9

Hi, I am getting this error message when trying to open a file that my predecessor worked on a couple of months ago. I have gone to the bak file and tried to open it by renaming it without the bak but when I try to open it I get the same error message.
Our IT section and myself have also run the Dcache program recommended by Adobe but it wasnt able to find the file.
Is there anything else that I can do to try and get this file open?
