iPad 2 problem

I installed Digital Editions (DE) on my iPad but didn't activate it before I clicked on the ebook download link. I then activated DE and I can see the ebook there but it won't downloadd. I get the following error message.

"Digital editions could not connect to the fulfillment server. please make sure you are connected to the internet." My internet connection is fine.

I have deleted DE from my iPad and re-installed it but I get the same error.

Any suggestions?