Question on Time delay...

I quote an example of *Closing Feedback Loops with Time Delays*at http://www.mathworks.cn/help/toolbox/control/ug/bstzkhr.html#bstz1u7

I get prompt like this

[red] ??? Undefined command/function 'pid'.[/red]

and when I change to tf form, I get

??? Error using ==> tf.feedback FEEDBACK cannot handle time delays.

What's matter? How to correct?

http://www.mathworks.cn/help/toolbox/control/ug/bstzkhr.html

G = tf(1,[1 10],'InputDelay',2.1) 
C= tf([0.5 2.3], [1 0])
%C = pid(0.5,2.3);
% C has a proportional gain of 0.5 and an integral gain of 2.3.
% Use feedback to compute the closed-loop response from r to y.
T = feedback(C*G,1);

Transfer function:
                1
exp(-2.1*s) * ------
              s + 10

Transfer function:
0.5 s + 2.3
-----------
     s

??? Error using ==> tf.feedback
FEEDBACK cannot handle time delays.

[Craig]

What version of MATLAB are you using?