How to run a model with reaction

Dear developers,

I am trying to run the simulation with a simple reaction(ozone decomposition). However, I could not even run a single step before the simulation automatically stoped:( I think it is due to the error in my UDF but I couldn’t figure it out cuz this is my first time doing this kind of simulation. So could you pls kindly take a look and tell me where went wrong? Thanks a lot!

Please attach your simulation files.