If it's U1900 or U1700 (can bus receive error) you get that on nearly every CMax (in instrument cluster I guess?)

If you try and connect without the ignition on it will eventually take you to that screen where you add the calibration number - the number you're trying to add is the part number. If you go to the 'trace' tab bottom left of screen (looks like a sheet of paper type image) when you've tried to connect, does it give any cal numbers there?

I guess it won't if the IDS can not recognise the number whilst trying to connect automatically.

As said earlier, the more the IDS is updated the less support it seems to have for older vehicles.

Just a thought, is the ECU being powered up? Power hold relay working etc?