Duplicate shortcut not working in Illustrator CS4?

Just come across this and found a quick solution.

I've used Illustrator for years and very often I'd 'alt drag' an object to copy it, then I'd use 'ctrl+d' (or Apple(cmd)+d on Mac), to duplicate my last action; very useful for creating a series of objects following a path.

For some reason this shortcut no longer works; I couldn't even find the 'Duplicate' option in the menu.

The fix is to 'alt drag' your object as you would normally; then, in this order, use:

'ctrl+c',
'ctrl+f',
then 'ctrl+d'

(Mac users swap the Apple (cmd) key in place of ctrl).