Linearization error in simulink

I was trying to learn simple tank model in simulink, following exact steps as mentioned in this tutorial video: https://in.mathworks.com/videos/trimming-and-linearization-part-2-the-practical-side-of-linearization-1544004777920.html.

While linearizing the model, I continuously received the following error:

Simulink model 'watertank' was called with an invalid flag

Component:Simulink Control Design | Category:Linearization error

Can someone help me with this issue?