'Error getting license. License server communication problem: E_ADEPT_DOCUMENT_TYPE_UNKOWN:'

I bought & downloaded a book from Google Play and when I open the .acsm file in ADE, I get the message 'Error getting license. License server communication problem: E_ADEPT_DOCUMENT_TYPE_UNKOWN:'

How do I solve this? I downloaded another book from Google play the same day and that downloaded fine after opening the .acsm file.

I'm using Windows 7.

I contacted Google regarding this, but they directed me here. Any help appreciated.

Thanks

Mark