eroor with acts as solr pagination undefined method `paginate_all_by_solr'

Hi,

  i have tried to paginate search result of acts as solr
by using following like
http://henrik.nyh.se/2007/06/using-will_paginate-with-acts_as_solr
and i am getting following error

undefined method `paginate_all_by_solr' for #<Class:0xb4fa5f0>

could any one provide me solution pls,

thanks,
-pab