Corona SDK的Director类在设备上出现错误。

我在使用 Director v1.4 进行设备测试（iPhone）时遇到了问题。模拟器没有显示任何错误，但设备上会出现错误。以下是错误信息：

slotMachine[1206] <Warning>: Runtime error
?:0: attempt to call method 'insert' (a nil value)
stack traceback:
    [C]: in function 'insert'
    ?: in function 'changeScene'
    ?: in function <?:13>
    ?: in main chunk

这是 main.lua 的代码：

    display.setStatusBar( display.HiddenStatusBar )

local director = require("director")

local mainGroup = display.newGroup()

local main = function ()

    mainGroup:insert(director.directorView)

    director:changeScene("menu1", "overFromBottom")

    return true
end

main()

这是 menu1.lua 的代码：

    module(...,package.seeall)

new = function ( params )

    local GGData = require( "GGData" )

local _W = display.contentWidth --Width and height parameters
local _H = display.contentHeight

    local localGroup = display.newGroup()
local box = GGData: load( "credits" )
local background = display.newImageRect("images/machine_bg.png",640,960)
background.x = _W*0.5;
background.y = _H*0.800;

local currentBalance = display.newText("Current Balance:\n$"..box.credits, 0,0,400,0, "Quicksand", 25)
currentBalance:setTextColor(44, 62, 80)
currentBalance:setReferencePoint(display.CenterLeftReferencePoint)
currentBalance.x = _W - 265; currentBalance.y = _H *0.17;

localGroup:insert (background)
localGroup:insert (currentBalance)

    return localGroup

end