Compile Error: "Type mismatch: cannot convert form null to double"

[zhang-zedong]

When I download this program and run it by the right edition of Anylogic, I got 10 errors which as the title says. I want to fix it, but I don't know where to start. So I pull this issue to determine whether I get the right configuration and know how to fix it. Thank you for your talent work!

[zhang-zedong]

I altered the "null" to the "0" and solved this problem. I'm studying your model, thanks again.