According to Evernote's new pricing, Evernote cannot create new note by e-mail, which is the way Twieve has been using.
You need to connect Evernote with Twieve to receive tweets in Evernote. Just login into Twieve and click"Connect Evernote". That's it. Your tweets will deliver as you have so far.
The old plan(using e-mail) will be available till August 31.