Redmine

access http://x.x.x.x:3000/projects/bbs/boards

err:
ActionView::TemplateError (undefined method `-' for {:length=>60}:Hash) on line #52 of app/views/boards/show.rhtml:
49: <td class="last_message">
50: <% if topic.last_reply >
51: <= authoring topic.last_reply.created_on, topic.last_reply.author ><br />
52: <= link_to_message topic.last_reply >
53: < end %>
54: </td>
55: </tr>

config/environment.rb:66:in `truncate'
    app/helpers/messages_helper.rb:22:in `link_to_message'
    app/views/boards/show.rhtml:52:in `_run_rhtml_app47views47boards47show46rhtml'
    app/views/boards/show.rhtml:43:in `each'
    app/views/boards/show.rhtml:43:in `_run_rhtml_app47views47boards47show46rhtml'
    app/controllers/boards_controller.rb:53
    app/controllers/boards_controller.rb:39:in `show'
    app/controllers/boards_controller.rb:34:in `index'
    /usr/local/ruby/lib/ruby/1.8/webrick/httpserver.rb:104:in `service'
    /usr/local/ruby/lib/ruby/1.8/webrick/httpserver.rb:65:in `run'
    /usr/local/ruby/lib/ruby/1.8/webrick/server.rb:173:in `start_thread'
    /usr/local/ruby/lib/ruby/1.8/webrick/server.rb:162:in `start'
    /usr/local/ruby/lib/ruby/1.8/webrick/server.rb:162:in `start_thread'
    /usr/local/ruby/lib/ruby/1.8/webrick/server.rb:95:in `start'
    /usr/local/ruby/lib/ruby/1.8/webrick/server.rb:92:in `each'
    /usr/local/ruby/lib/ruby/1.8/webrick/server.rb:92:in `start'
    /usr/local/ruby/lib/ruby/1.8/webrick/server.rb:23:in `start'
    /usr/local/ruby/lib/ruby/1.8/webrick/server.rb:82:in `start'

Rendering /var/www/redmine.0.9.3/public/500.html (500 Internal Server Error)