Ruby - NameError: uninitialized constant. Using class from a different module

I have these 2 files in a large system, both are located in PackA

1. people.rb

module People
  class HobbyValueObject
  end
end

2. job.rb

module People
  class Job
  end

  class CityValueObject
  end
end

I am trying to use CityValueObject in a different module like this,

Module is in PackB

3. work.rb

module Profile
   class Work
       ....
       def calculateTaxes
          ...
          a = People::CityValueObject....
       end
   end
end

But it's giving me an error saying,

NameError: uninitialized constant People::CityValueObject

Did you mean? People::HobbyValueObject

Why is not being able to fine CityValueObject but can find HobbyValueObject just fine? How do I make it find the object that I am intending to use?

I am not explicitly declaring any requires or includes