getComponent("GUIComponent") return a nil value in lua

[weyson]

this is my code:
local node = ccs.SceneReader:getInstance():createNodeWithSceneFile(“ccs/scene_game.json”)
local uiNode = tolua.cast(node:getChildByTag(10003), “Node”)
local render = tolua.cast(uiNode:getComponent(“GUIComponent”), “Component”)
I use scene include a ui, finially render is nil value.