Copying my Adobe Digital Editions library from one laptop to another

I have set up ADE 3.0 on my new laptop and copied my .acsm files over, but when I try to import the .acsm files into ADE I get the following message:

Unable to download - Error getting License. License Server Communication Problem: E_LIC_ALREADY_FULFILLED_BY_ANOTHER_USER

Presumably the other user is me on my old laptop? How can I get authorisation to access my books on my new laptop?