rails cells 又呼叫其它的partial

http://cells.rubyforge.org/
我利用 rails cells 這個gem 做一個 partial

然後這個partial 的html 又要去呼叫 view 裡頭的一個partial

結果會missing partial

我的資料結構是這樣

app/cells/dialogue/child_post.html.erb
app/cells/dialogue_cell.rb
app/views/users/_avatar.html.haml

我的 child_post.html.erb
`......
<%= render :partial => "users/avatar", :locals => { :avatar => post.user.avatar, :opts => { :size => 'small' }} if post.user.present? %>
....
`
想說是相對路徑，我試著這樣寫

<%= render :partial => "../../views/users/avatar", :locals => { :avatar => post.user.avatar, :opts => { :size => 'small' }} if post.user.present? %>

也是無效說

有人知道該怎麼呼叫嗎？感謝