getting error using discrete transfer function

Hello ,

      I want to implement notch filter using discrete transfer function block using simulink...

for this i have take example from mathworks

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ST0 = slTunable('new22',{'NOTCH'});

wn = realp('wn',300);

zeta1 = realp('zeta1',1); zeta1.Maximum = 1; % zeta1 <= 1

zeta2 = realp('zeta2',1); zeta2.Maximum = 1; % zeta2 <= 1

N = tf([1 2*zeta1*wn wn^2],[1 2*zeta2*wn wn^2]); % tunable notch filter

ST0.setBlockParam('Notch',N);

*****************************************

but i am getting error when i am associating these parameters to block

what is the error means

"The sample time after propagation is [0, 1]. Enter a discrete sample time in 'new22/NOTCH'"

where should i enter discrete sample time ?