I had this same problem at first. I found that if the epub file was blocked by Windows 7 (my current OS) then I couldn't perform a simple copy command. To see if your file is blocked, navigate to the folder where the epub resides and right click > properties. On the General tab at the bottom you may see a button that says unblock. Press that and the features you are missing will become available. I know this response is late but maybe it will help someone else.
I've done that, but it is still not possible to copy and paste text.
same issue here
Adobe Digital Editions is probably the *worst* piece of software I have used. I will not buy books that are use this format. However, I have one book and have found a way to extract the annotations. It is a kludge. I use a Mac so apologies for PC users, but I am sure it will translate.
Annotations are stored in a "*.annot file" in the same folder as the original. You can open this file using a bog-standard text editor. If you haven't seen XML before don't freak out.
Copy the XML code.
Go to http://codebeautify.org/xmlviewer and paste the XML into the LH window (XML input). Then between the LH window and the RH window is a panel with some options. Click "Export to CSV". This will download a comma separated values file that can be read by Excel.
When you open it up in Excel you will find all of your comments have been extracted and all the other XML guff has been cleared away. There are some horrible Ascii conversions going on, but at least you can read the comments.
The fact that you have to do through all of these kludgy stages just to get your comments shows what a terrible piece of software ADE is. I would rather buy a hard copy of a book than an ADE version.
The problem is often that the creater of the eBook not want that text was copy. Has you check the perssion of the eBook?