title: Corona Runtime Error "attempt to concatenate field '?' (a nil value)"
body: <p>i have this 8 question survey in my mobile application handover project. At first the corona did not prompt me any error message and the app works just fine but when i add 2 more question to it i start getting this message error
  <a href="https://i.stack.imgur.com/CIG2X.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/CIG2X.png" alt="enter image description here"></a>
  i am not sure why the error is "a nil value" but my code look something like this.(line 662 to 678)<br></p>
  
  <pre><code>        function  checkEBASComplete()
          local tempScore = 0
          for i = 1, 10 do
              print("EBAS:"..ebasRating_Arr[i])
              tempScore = tempScore + ebasRating_Arr[i]
  
              if (ebasRating_Arr[i] == -1) then
                  ebasScore = 0
                  ebasScore_text.text = "Test Incomplete"
              else
                  ebasScore = tempScore
                  ebasScore_text.text = tostring(ebasScore)
              end
  
          end
  
          tempScore = 0
      end
  
      checkEBASComplete()
  </code></pre>
  
  <p>and i have something like this at line 110. i just add 2 more "-1" behide</p>
  
  <pre><code> local ebasRating_Arr = {-1,-1,-1,-1,-1,-1,-1,-1,-1,-1}
  </code></pre>
  
  <p>Is anyone able to help me with this? Appreciate for all helps :D</p>
  
  <p>NEW QUESTION------------------------------------------------------</p>
  
  <p><a href="https://i.stack.imgur.com/4MVux.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/4MVux.png" alt="enter image description here"></a>
  this is my code from line 705 - 711</p>
  
  <pre><code>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
  </code></pre>