Thank you for the quick reply. When I hit the "rec" button in the gui it says "ERROR: not connected" even though the "Files" tab still works and linbus is still listed in the top right drop down.
I'm fairly sure that "not connected" error can only appear if it's actually not connected.
The dot at the top left where it says host: ... cam: ... should be green when connected. The camera will be listed in the dropdown even if chdkptp isn't connected.
So first, make sure you've plugged the camera in while it's in playback mode, and hit the "connect" button to connect.
If clicking rec button while connected does actually generate the "not connected" error, does anything other happen? That is, does the camera respond in any way like shutting off or extending the lens, or are any other message printed?