Any idea of this exception?

NoMethodError (undefined method <=' for nil:NilClass): /vendor/plugins/expiring_action_cache/lib/actionparamcache.rb:84:inbefore’
/vendor/rails/actionpack/lib/action_controller/filters.rb:242:in
prepend_around_filter' /vendor/rails/actionpack/lib/action_controller/filters.rb:401:incall_filters’
/vendor/rails/actionpack/lib/action_controller/filters.rb:394:in
call_filters' /vendor/rails/actionpack/lib/action_controller/filters.rb:383:inbefore_action’
/vendor/rails/actionpack/lib/action_controller/filters.rb:365:in
perform_action_without_benchmark' /vendor/rails/actionpack/lib/action_controller/benchmarking.rb:69:inperform_action_without_rescue’
/home/pierocampanelli/extra/lib/ruby/1.8/benchmark.rb:293:in
measure' /vendor/rails/actionpack/lib/action_controller/benchmarking.rb:69:inperform_action_without_rescue’
/vendor/rails/actionpack/lib/action_controller/rescue.rb:82:in
perform_action' /vendor/rails/actionpack/lib/action_controller/base.rb:408:inprocess_without_filters’
/vendor/rails/actionpack/lib/action_controller/filters.rb:377:in
process_without_session_management_support' /vendor/rails/actionpack/lib/action_controller/session_management.rb:117:inprocess’
/vendor/rails/railties/lib/dispatcher.rb:38:in dispatch' /vendor/rails/railties/lib/fcgi_handler.rb:150:inprocess_request’
/vendor/rails/railties/lib/fcgi_handler.rb:54:in process!' /home/pierocampanelli/extra/lib/ruby/site_ruby/1.8/fcgi.rb:600:ineach_cgi’
/home/pierocampanelli/extra/lib/ruby/site_ruby/1.8/fcgi.rb:597:in
each_cgi' /vendor/rails/railties/lib/fcgi_handler.rb:53:inprocess!’
/vendor/rails/railties/lib/fcgi_handler.rb:23:in `process!’
dispatch.fcgi:34