entities.rb

require 'fog/core/collection'
require 'fog/rackspace/models/monitoring/entity'
require 'fog/rackspace/models/monitoring/check'

module Fog
  module Rackspace
    class Monitoring
      class Entities < Fog::Collection

        model Fog::Rackspace::Monitoring::Entity

        attribute :marker

        def all(options={})
          data = service.list_entities(options).body
          marker = data['metadata']['next_marker']

          load(data['values'])
        end

        def get(entity_id)
          data = service.get_entity(entity_id).body
          new(data)
        rescue Fog::Rackspace::Monitoring::NotFound
          nil
        end

        def overview(options={})
          body = service.list_overview(options).body
          marker = body['metadata']['next_marker']

          load_all(body['values'])
        end

https://gist.github.com/elight/7995258#file-entities-rb-L15-L16

Shouldn't that be: self.marker? Otherwise marker is a local var.