"Extrude poly ribbon" (ctrl+click) not working for me So I've been following this blender tutorial and have just created a head using Dyntopo.  I am now learning how to finish it with retopo.  I started out by turning on snap during transform (snap element: edges, snap target: active), and positioned a small plane the head.  The tutorial then went on to explain how to "extrude a poly ribbon" by selecting an edge of the plane and extruding it by pressing control and clicking, as shown below: 



When I try to do this, however, it does not seem to work.  It just outlines the head in orange, as shown:



What should I try doing differently to make this work for me? If it matters, I am using a mac.
Mac: If the answers above don't work for you, try: &#9096; Ctrl&#8984; Cmd LMB

In order for &#9096; Ctrl&#8984; Cmd LMB to work, you must have "Emulate 3 Button Mouse" checked.

To do this: File > User Preferences > Input tab > check Emulate 3 Button Mouse box