I have a subroutine in an application and I am trying to hook it to a different one and it does not work

The hook is restricted by database and user. Any ideas?

You can't hook a subroutine that you invoke from a GOSUB or COPY. The hook mechanism only works when you invoke a process - that means that you can hook a subroutine that you invoke with a SUBR statement, or a subroutine that you invoke as an optional or automatic child.