Don't let FOO::Indicators::PPO inherit from FOO::Indicators, but make it a subclass of Foo.

Thanks! That did it, but now I have a new question: what happens with the methods I had in FOO::Indicators? I tried moving them to FOO and it works but I guess there's a better solution.

Did you consider using DBIX::Class instead of Class::DBI?

The truth is that I didn't. I found Class::DBI when searching for something, and then I didn't know that there were more modules available for that. Maybe in a future rewrite...