Error with the SIR Model

Hello, I am trying to simulate the SIR Model considering N=S+I+R. I get the following errors, concerning the plot, where a variable is not being plotted. Is there anyone who can help me? Thank you

This is the sirn_model_definition file where I declared and defined my parameters:

This is the sirn_model file where I defined the function:

[Sam Chak]

Unable to debug images of codes.

Answer 1

[Alan Stevens]

1. Update N at each timestep.
2. Plot I and R on a different scale from S.