how to use the model which is done by System identification toolbox?

I used the input and output in the SI then get the transfer function with the high validaton for example I got the G11 asa model which is come form the input and out put. I want to use this model to check the output of the system in other system. but when ever I used the model with the same input it shows me different output any body can help me? tanx in advanced

Answer 1

[Rajiv Singh]

Did you set the initial conditions correctly?

See: http://www.mathworks.com/matlabcentral/answers/72338-how-fix-the-problem-of-the-initial-state