As a guess, I'd say that the tool won't run because the drive is already too far gone.
You might see what this tells you: HDDScan
For what it's worth, as soon as you get a warning that a drive has problems you can just about forget it. It might last five weeks or five minutes, but it's not going to last five years. You were very smart to back your stuff up while you could. I would plan for a new drive as soon as possible; right now if you really need the machine on a regular basis.