fix a bug I introduced

app/controllers/tags_controller.rb

@@ -54,7 +54,7 @@ class TagsController < ApplicationController
       @posts = StatusMessage.all_public
     end
 
-    @posts = @posts.tagged_with(params[:name]).for_a_stream(max_time)
+    @posts = @posts.tagged_with(params[:name]).for_a_stream(max_time, 'created_at')
 
     @commenting_disabled = true
     params[:prefill] = "##{params[:name]} "

app/models/post.rb

@@ -42,7 +42,7 @@ class Post < ActiveRecord::Base
     limit(15)
   end
 
-  def by_max_time(max_time, order='created_at')
+  def self.by_max_time(max_time, order='created_at')
     where("posts.#{order} < ?", max_time).order("posts.#{order} desc")
   end
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