I'm trying to create a timestamp with both date and time in org-mode (without adding to agenda), and I read from [the docs](http://orgmode.org/manual/Creating-timestamps.html) that I should be using this cord:

> C-u C-c !

However, I get this in my minibuffer:

![screenshot](http://zc.d.pr/NxKK/56UjyS0K+)

Seems like its waiting for more input. I'm an Emacs n00b so I'm not really sure what's happening here. I get the same behavior with 

> C-c !

Both versions with `.` work fine, though:

> C-u C-c .

> C-c .

What's happening here?