how to add variables in response optimization (sdotool)

i try to use simulink design optimization toolbox to solve my problem. so i followed the simulink example to execute. but i had a problem in my case about design variables set. in the matlab example(Hydraulic Cylinder Model), the variables could be snowed automatically.

but in my case , there is nothing in the right section.

what is the problem in my case or what should i set or link something in the program

thanks for your help.