You have a nil object when you didn't expect it!

hi
i have erorr

You have a nil object when you didn’t expect it!
You might have expected an instance of ActiveRecord::Base.
The error occurred while evaluating nil.[]

sinin.rhtml

<%form_for :member,:url=>{:action=>:signin} do |form|%>

UserName : <%text_field :member,:member_id,:size=>25%>

Password :<%tetx_field :member,:member_password,:size=>15%>

<input type="submit" value="signin" <%end%>

Controller

class MemberController < ApplicationController
def signin
account = params[:member][:member_id]
password = params[:member][:member_password]
@u = Member.find(
:first,
:conditions=>[“member_id=? AND member_password=?”,account,password])
if @u
flash[:notice] = “#{@u.login}, you’ve logged in successfully”
else
redirect_to :controller => ‘sessions’, :action => ‘new’
end
end
end

Help me
Thank you