Unable to use a value of type struct as an index

Hi, everyone.
I am trying to run a mod file using Dynare 6.2, I got errors like:

but MODEL_DIAGNOSTICS: No obvious problems with this mod-file were detected.

I searched the forums but couldn’t find any relevant discussions. Could you please help me understand the possible causes of this issue and suggest how to resolve it?

Without the file it is impossible to tell.