问ruby on rails作用域- ArgumentError:错误的参数数量(0对应1)

EN

Report.start_driver_time(Unit.find(3007),Driver.find(2),3,2013)

  scope :start_driver_time, lambda { |unit, driver, month, year|
    where("unit_id = ? AND
          driver_id = ? AND
          extract(MONTH FROM time) = ? AND
          extract(YEAR FROM time) = ?",
          unit.id, driver.id, month, year)
    .order("time asc")
    .min(:time)
  }
 #select(:time) select([:id, :time])

  scope :next_driver_time, lambda {|unit, time|
    joins(:alerts => {:alert_code => :alert_unit_codes})
    .where("reports.unit_id = ? AND
            reports.time >= ? AND
            alert_unit_codes.name = ?",
            unit.id, time, "Seat Belt OFF")
    .min(:time)        
  }

  scope :reports_within_driving_period, lambda { |start_time, end_time|
    where("unit_id = ? AND
            reports.time >= ? AND
            reports.time <= ?",
            start_time, end_time)
  }

ArgumentError: wrong number of arguments(1 for 0)
    from /Users/johnmerlino/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.5/lib/active_record/relation/delegation.rb:37:in `min'
    from /Users/johnmerlino/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.5/lib/active_record/relation/delegation.rb:37:in `method_missing'
    from /Users/johnmerlino/Documents/github/XKTrackingSystem/app/models/report.rb:40:in `block in <class:Report>'
    from /Users/johnmerlino/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.5/lib/active_record/scoping/named.rb:180:in `call'
    from /Users/johnmerlino/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.5/lib/active_record/scoping/named.rb:180:in `block (2 levels) in scope'
    from /Users/johnmerlino/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.5/lib/active_record/scoping/default.rb:41:in `block in unscoped'
    from /Users/johnmerlino/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.5/lib/active_record/relation.rb:241:in `block in scoping'
    from /Users/johnmerlino/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.5/lib/active_record/scoping.rb:98:in `with_scope'
    from /Users/johnmerlino/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.5/lib/active_record/relation.rb:241:in `scoping'
    from /Users/johnmerlino/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.5/lib/active_record/scoping/default.rb:41:in `unscoped'
    from /Users/johnmerlino/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.5/lib/active_record/scoping/named.rb:180:in `block in scope'
    from (irb):1
    from /Users/johnmerlino/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.5/lib/rails/commands/console.rb:47:in `start'
    from /Users/johnmerlino/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.5/lib/rails/commands/console.rb:8:in `start'
    from /Users/johnmerlino/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.5/lib/rails/commands.rb:41:in `<top (required)>'
    from script/rails:6:in `require'
    from script/rails:6:in `<main>'1.9.3p0 :002 > exit