Am I out of luck with this adapter?
I think so, it sounds like another marginal adapter that doesn't have quite enough power for the cam, and 1.1V/cell on load is near end-of-life cell voltage for cam operation.
An old 5V @ 1A external ZipDisk adapter would work (with proper DC connector added -- if you or a friend do soldering), or you need to shop for an adapter with better voltage, at least 4.8V, but not much over 6V (< 6.3V at a guess)
I found a Canon adapter (ACK800, 3V) on ebay for my cam at about a third retail price, they're rare.