问CoronaSDK控制器错误

EN

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--
-- main.lua
--
-----------------------------------------------------------------------------------------

local director = require("director")
local mainGroup = display.newGroup()
splash = display.newImage("images/logo.png")

local main = function()

    splash:removeSelf()
    splash = nil
    mainGroup:insert(director.directorView)
    local widget = require "widget"

    -- show default status bar (iOS)
    display.setStatusBar(display.DefaultStatusBar)

    local mainGroup = display.newGroup()

    -- event listeners for tab buttons:
    local function onFirstView( event )
        director:changeScene("startUp")
    end

    local function onSecondView( event )
        director:changeScene("home")
    end

    -- table to setup buttons
    local tabButtons = {
        { label="Home", up="icon1.png", down="icon1-down.png", width = 32, height = 32, onPress=onFirstView, selected=true },
        { label="Cards", up="icon2.png", down="icon2-down.png", width = 32, height = 32, onPress=onSecondView },
    }

    -- create the actual tabBar widget
    local tabBar = widget.newTabBar{
        top = display.contentHeight,
        buttons = tabButtons
    }

    --I think it is this line which is causing the error
    director:changeScene("startUp")

    return true
end

timer.performWithDelay(3000, main, 1)

module(..., package.seeall)

function new()
    require "sqlite3"
    local director = require("director")
    --Connect to database or create it.
    --Each user gets there own database****
    local path = system.pathForFile("data.db", system.DocumentsDirectory)
    local db = sqlite3.open(path)

    --Create the database table if it does not already exist
    local tablesetup = [[CREATE TABLE IF NOT EXISTS User (id Integer autoincrement PRIMARY KEY, firstname, lastname);]]
    db:exec(tablesetup)

    for row in db:nrows("SELECT * FROM User") do
        --goto home if the user is in the database.
        director.changeScene("home")
    end

    --If not in the database go to forms
    director.changeScene("forms")

    --Catch application Exit
    Runtime:addEventListener("system", onSystemEvent)

    --Handle application exit - close the database connection
    local function onSystemEvent(event)
        if(event.type == "applicationExit") then
            db:close()
        end
        print("database closed")
    end

end

Runtime Error director.lua:1092:attempt to call method 'insert' (a nil value) 
stack traceback: in function 'insert' in function 'changeScene'
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Director Error: Failed to execute new(params) function on 'startUp'.
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assertion failed
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