Searchlogic incompatible with error_messages

Is searchlogic incompatible with error_messages? I am following the
example at #176 Searchlogic - RailsCasts. If I add
<%= f.error_messages %> to the form I get the error below:

Showing index.html.erb where line #2 raised:

undefined method `errors’ for #Class:0x1035a7a18

Extracted source (around line #2):

1: <% form_for @search do |f| %>
2: <%= f.error_messages %>

Please help. Thanks.