Control System Analysis Techniques course error

In the Time domain section of the course when I use the step function to plot the grpah it keeps saying i am wrong even though it is the exact same code and graph. Those anyone have anny solutions

below is the code

s = tf('s');
quadcopter_ol = 0.04133/(s + 0.01479);
controller = zpk(-5,0,100);

Task 1

step(quadcopter_ol)

[Walter Roberson]

Is it look for step(controller) ?

s = tf('s');
quadcopter_ol = 0.04133/(s + 0.01479);
controller = zpk(-5,0,100);
step(controller)