Error Running Non Linear Time History Analysis

[darmawan]

Thank you, now it works.

Then, I try to modify my model. I model the slab using face instead of frame element (edge). Then I assign the self-weigth & mass of the slab using forceFace and massFace. But now the model error. I try to follow the 3rd Getting Started in OpenSees with STKO webinar. I still did not capture what the problem is. What is going on?