lua corona 运行时错误：尝试在字段'?'(空值)上执行算术运算

我正在尝试使用 Corona 显示表单摘要。一开始可以，但当我添加了 2 个新问题时，就会出现错误

以下是第 15 个场景的代码

--line689   checkEBASComplete()

--line691   function  checkAMTComplete()
            local tempScore = 0
            for i = 1, 11 do
--line694   tempScore = tempScore + amtRating_Arr[i]
            if (amtRating_Arr[i] == -1) then
                amtScore = 0
                amtScore_text.text = "测试未完成"
            else
                amtScore = tempScore
                amtScore_text.text = tostring(amtScore)
                end

                end

                tempScore = 0
                end
--line707   checkAMTComplete()

    function saveResults()

        local q = [[UPDATE EBAS_DEP SET rating1=']]..ebasRating_Arr[1] .. [[',rating2=']] .. ebasRating_Arr[2] .. [[',rating3=']] .. ebasRating_Arr[3] .. [[',rating4=']] .. ebasRating_Arr[4] .. [[',rating5=']] .. ebasRating_Arr[5] .. [[',rating6=']] .. ebasRating_Arr[6] .. [[',rating7=']] .. ebasRating_Arr[7] .. [[',rating8=']] .. ebasRating_Arr[8] .. [[',rating9=']] .. ebasRating_Arr[9] .. [[',rating10=']] .. ebasRating_Arr[10] .. [[',rating11=']] .. amtRating_Arr[1] .. [[',rating12=']] .. amtRating_Arr[2] .. [[',rating13=']] .. amtRating_Arr[3] .. [[',rating14=']] .. amtRating_Arr[4] .. [[',rating15=']] .. amtRating_Arr[5] .. [[',rating16=']] .. amtRating_Arr[6] .. [[',rating17=']] .. amtRating_Arr[7] .. [[',rating18=']] .. amtRating_Arr[8] .. [[',rating19=']] .. amtRating_Arr[9] .. [[',rating20=']] .. amtRating_Arr[10] .. [[',rating21=']] .. amtRating_Arr[11] .. [[',ebas_score=']] .. ebasScore ..[[',amt_score=']] .. amtScore ..  [['WHERE id=']].. _G.EBAS_ID..[[';]]
        db:exec( q )
        print(db:errcode(), db:errmsg())

    end

请问有人能提供建议吗？谢谢