更新失敗，命名空間模式

我有一個管理用戶的Rails 3中的更新表單，儘管有驗證失敗，但無提示失敗。它是以前工作，但是當我將所有內容移動到名稱空間時，它不再保存。更新失敗，命名空間模式

這裏是我的控制器相關代碼：

def update 
    @admin = Admin::Admin.find(params[:id]) 

    respond_to do |format| 
     if @admin.update_attributes(params[:admin]) 
      flash[:success] = "'#{@admin.name}' was successfully updated." 
      format.html { redirect_to admin_admins_path } 
     else 
      format.html { render action: "edit" } 
     end 
    end 
end

和模型（未完，但以前工作）：

class Admin::Admin < ActiveRecord::Base 
    validates :name, :presence=>{:message=>"Name can't be blank"} 
    validates :email, :presence=>{:message=>"Email can't be blank"}, 
     :length => {:minimum => 3, :maximum => 254, :message=>"Email must be between 3 and 254 characters"}, 
     :uniqueness=>{:message=>"Email has already been registered"}, 
     :format=>{:with=>/^([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})$/i, :message=>"Email must be a valid email format"} 
    validates :password, :presence=>{:message=>"Password can't be blank"} 
end

和窗體的部分第一部分：