API Problem with wordpress.com stats

I see many posts about this but am unable to resolve it.

On activating the ‘wordpress.com stats’ plugin after upgrading from 2.3.1 to 2.3.2 I get:

Error from last API Key attempt:
The owner of that API Key (markmelch) is not on the access list for this blog. When this blog was registered, markmelch’s API key was used. To add you to the access list, markmelch must visit this blog’s stats dashboard page and use the form at the bottom of that page.
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The WordPress.com Stats Plugin is not working because it needs to be linked to a WordPress.com account.
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Enter your WordPress.com API key to link this blog to your WordPress.com account. Be sure to use your own API key! Using any other key will lock you out of your stats.

The API is owned by markmelch.wordpress.com and is used at medicalqigong.wordpress.com, artist.melchiorre.com, and family.melchiorre.com. It is family.melchiorre.com that I am having trouble with. markmelch is an admin on all sites.

On the 3 sites that I can access stats all 4 appear in the switch drop down.

Only artist.melchiorre.com has an ‘add user’ form on the stats page.

Thanks in advance for your help.