NoMethodError: You have a nil object when you didn't expect

Hi,

I have tried to use searchlogic in my application…
in def index,
@search = AccounDetail.search(params[:search])
@account_details = @search.all

In index.rhtml
<%form_for @search do |f|%>

<%=f.label :name_like,"Name"%> <%=f.text_field :name_like%> <%=submit_tag :Search,:name=>nil%>

<%end%>

I didn’t get any search result…
i tried it with ruby script/console.
when i call @search.all, i got “NoMethodError: You have a nil object
when you didn’t expect”

example

search=AccountDetail.search(:name_like_any=>“xx”)
search.all

give me a suggestion to solve this problem