The Powershot G16 needs LR 5.2 or newer to work:
LR needs OSX 10.7.x or newer to work
You can try the DNG Converter 8.2 and see if it’ll run on your OS, and if so, then convert the G16 raw files to DNGs and those will open in your older LR4:
Thanks for this. It's LR that's the problem. My OSX is fine. Will look at the converter and see if this works.