My Simulink results of a delayed discrete transfer function differs from lsim output

I am trying to simply simulate a model I obtained from the system identification toolbox. The model is a discrete model with an input delay. However, the results from simulating with the command 'lsim' is different from what I get from simulink. The output from 'lsim' is similar to what I expect to get but the results from the simulatiom is wrong. I am simulating the model both in MATLAB and SIMULINK with the input 'u' which is a two-column matrix with the first column for the simulation time and the second column for the corresponding input.

>> tf1=tf([0,5.1095],[1,-1.9924,0.9924],1,'IODelay',261)

tf1 =

5.109

z^(-261) * ----------------------

z^2 - 1.992 z + 0.9924

Sample time: 1 seconds

Discrete-time transfer function.

>> y_lsim=lsim(tf1,u(:,2),u(:,1));

>> out=sim('system_simulation.slx');

A view from the simulink file ''system_simulation.slx'' :

Solver is fixed-step with 1s as the step time.

>> plot(out.tout,y,out.tout,y_lsim,'r--')