The AppMod.src file is the main module that acts as directory of all the code files that will be used for the application. No code is present in an AppMod.src file; rather, it is used to declare the variables and modules belonging to your application.
The AppMod.src module must be replaced with one that simply declares a series of variables and modules. This module simply acts as a template for the actual VTS code to run and no code is present in a VTS AppMod.src file.
AppMod.src is described in detail in Interpreting the AppMod.src File for a Script Application.