E_LIC_ALREADY_FULLFILLED_BY_ANOTHER_USER

HELP! I have bought an Ebook from www.world-of-digitals.com. I have downloaded it to my desktop as a ".acsm" file. There support says I should be able to open it in Digital Editions but I am getting an error message. I have created an adobe account and have authorized the software before downloading. Am I missing something here?