在Corona/LUA中移动至下一个场景。

我已经尝试了一段时间，但没能成功。我试图使得当你点击 playButton 时，场景会切换到 scene2。

以下是代码：

local storyboard = require( "storyboard" )
local scene = storyboard.newScene()

---------------------------------------------------------------------------------
-- YOUR IMPLEMENTATION HERE
---------------------------------------------------------------------------------

local image, playButton, helpButton, text3, memTimer
print("test")

-- Touch event listener for background image
local function onSceneTouch( self, event )
    if event.phase == "began" then

        storyboard.gotoScene( "scene2", "slideLeft", 800  )

        return true
    end
end

-- Called when the scene's view does not exist:
function scene:createScene( event )

    local screenGroup = self.view

    image = display.newImage( screenGroup, "openingbackground.png" )
    image.x = _W * 0.5
    image.y = _H * 0.5
    screenGroup:insert( image )

    playButton = display.newImage( "playbutton.png" )
    playButton.x = _H * 0.33
    playButton.y = _W * 0.90
    playButton.xScale = 0.5
    playButton.yScale = 0.5
    playButton.touch = onSceneTouch
    screenGroup:insert( playButton )

    helpButton = display.newImage ("helpbutton.png")
    helpButton.x = _H * 0.33
    helpButton.y = _W * 1.1
    helpButton.xScale = 0.5
    helpButton.yScale = 0.5
    screenGroup:insert( helpButton )

    playButton:addEventListener("touch", playButton)

end

-- Called immediately after scene has moved onscreen:
function scene:enterScene( event )

end

-- Called when scene is about to move offscreen:
function scene:exitScene( event )

    print( "1: exitScene event" )

    -- remove touch listener for image
    image:removeEventListener( "touch", image )

    -- cancel timer
    timer.cancel( memTimer ); memTimer = nil;

    -- reset label text
    text2.text = "MemUsage: "
end

-- Called prior to the removal of scene's "view" (display group)
function scene:destroyScene( event )

    print( "1: destroyScene event" )

end

---------------------------------------------------------------------------------
-- END OF YOUR IMPLEMENTATION
---------------------------------------------------------------------------------

-- "createScene" event is dispatched if scene's view does not exist
scene:addEventListener( "createScene", scene )

-- "enterScene" event is dispatched whenever scene transition has finished
scene:addEventListener( "enterScene", scene )

-- "exitScene" event is dispatched before next scene's transition begins
scene:addEventListener( "exitScene", scene )

-- "destroyScene" event is dispatched before view is unloaded, which can be
-- automatically unloaded in low memory situations, or explicitly via a call to
-- storyboard.purgeScene() or storyboard.removeScene().
scene:addEventListener( "destroyScene", scene )

---------------------------------------------------------------------------------

return scene

我遇到的错误是：

Corona Runtime Error: ?:0? attempt to index a nil value stack traceback: ... Do you want to relaunch the project?

有人有什么想法吗？