I’m a new user with Endnote X7 for Mac (for few hours actually).
After building reference library I entered the URL of my Hospital’s Medical Library + authentication. While trying the “find full text” option, Endnote cannot retrieve the full text from journals in the library. When entering the journals from the Library’s website, I can find and attach manually the PDF to the relevant reference.
Before trying to authenticate/search for articles did you set the Find Full Text “preference” settings? Refer to this training video and instructions from the Endnote knowledge base: http://endnote.com/kb/82212
Note that if you’re affiliated with an institution that allows access to an OpenURL server, you can configure the Find Full Text preferences panel to allow EndNote access to the site. (You can check with a librarian for info.)