unable to create SIL test harness

I want to make a SIL test harness of the marked subsystem. I am working on MATLAB 2017a and have installed Embedded Coder and Simulink Testing toolbox. But I am not getting the create test harness option on right clicking on the subsystem. Can anyonye tell me what is my mistake?

[Jesús Zambrano]

Before doing that, note that Test harnesses attached to Subsystem models do not support SIL/PIL verification. See more details here https://www.mathworks.com/help/sltest/ug/relationship-between-harness-and-model-block-diagrams.html