Cannot open book on my e-reader

Hi,

I've got a Sony E-reader. I've downloaded several free books - no problems.

But recently i bought some books on a famous website. I downloaded them with ADE ( and at this moment, on my computer, I can open it and read the books), et then, put them on my e-reader.

When I want to open the books on my E-reader, i'm asked for my Adobe ID and password. And each time, i'm back to that screen that ask me ID and password, i cannot go further (and read my book !!) I'm sure my ID and password are right, cause I can use it to access my account on the website. And there's no error message like "wrong  password " or "not recognized"...no, i'm just back to the same screen again and again.

Does someone knows how to solve that problem ? I've contacted Sony as well, but without results so far...

Thank you very much !

ps : I'm french, so excuse my english