I am supposed to find the stability of my closed loop system using Nyquist stability in Matlab

Hi all , I am looking to find the stability for a closed loop system with delay . I have written a small program in Matlab:

kp =0.25;
kd = 2;
ki = -40;
t = (1+s)/(((s^2)+s-(exp(-2*s))));
p = ((kd*s^2)+(kp*s)+ki)/s; 
r = (p*t)/(1+(p*t));
nyquist(r);

But I donot know how to determine the stability from the plot that appears when i execute this program. I know that the nyquist stability criterion but for a delay case as above im confused. A help from someone would be greatful. Thanx in Advance

[Azzi Abdelmalek]

Have you tried your code on Matlab?

[Raghavendran Srinivasan]

yes I am getting a plot but i dunno how to say the stability from the plot!! And there is a warning that says the values were obtained by substituting zero for the time delay !!!