Have you checked whether it's turned on in Edit > Keyboard Shortcuts?
Yep - it's turned on, all default settings.
Only installed CC yesterday
Have you tried changing the shortcut in Keyboard Shortcuts? Create and save a new set and choose a different shortcut.
This usually happens because there is some third-party software capturing keystrokes. Could be a browser extension, for example.
New command assigned 'control+D' now works!