更新失败，命名空间模式

我有一个管理用户的Rails 3中的更新表单，尽管有验证失败，但无提示失败。它是以前工作，但是当我将所有内容移动到名称空间时，它不再保存。更新失败，命名空间模式

这里是我的控制器相关代码：

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

和窗体的部分第一部分：