I have downloaded the new installer - DataFlex Reports Runtime 64 bit - but when the user runs it (he has to: I don't have permissions on his workstation - I can only watch him perform Administrator-level operations) it just says another version of the product is already installed.

So... do I have to do (or rather have him do) an uninstall first?

I also tried having him run: regsvr32 "C:\Program Files\DataFlex Reports Runtime 8.1 64 bit\DataFlex Reports 2022 Developer Edition API64.ocx", as I mentioned in my reply to Stephen, which was (eventually, once we'd fixed the typos ) successful, but didn't fix the problem.