Keynote 6.6.2 glitch

I am no further forward with this problem, which I posted about a couple of weeks ago. The error message is in the screen shot

I am running the latest version: 6.6.2. When I right click the presentations that cause this message to appear I get the option to "show package contents" and it is clear that the index package is missing. Why would this be and how can I fix it?

Thanks,

Jim