Smart Tab : indenting with C-u <tab> does not work (beginning of a line)

Question

(I haven't find any answer in previous topics)

I am using Smart Tab globally, i.e. I have put the following code in my .emacs :

(require 'smart-tab)
(global-smart-tab-mode 1)

I am writing a program in Fortran, and I often need to indent some lines, which, according to smart-tab documentation, is done either by prefixing the smart-tab command (i.e. <tab>) by C-u or by selecting the region to be indented before hitting <tab>.

After some research, I still don't understand why only the "selecting a region" method works for me : to indent just one line, I need to have it selected, but C-u <tab> does not work, and always gives to following message (which I don't understand) :

Symbol's function definition is void: cl-case

Being able to indent any line (and just one line) by using <tab> in a simple command would solve my problem (while keeping smart-tab).

Answer 1

As said in the comments on my question, adding (require 'cl) to my config file solved my problem (following DoMiNeLa10's suggestion).

N.B.: I am using Emacs 24.3.1.