getElementByName not work with elements that created on the fly

See more:

Javascript

I build a website that demonstrate finnacial website for investments. so I give to the clients option to answer questionnaire befor advice to them portfolio. the questionnaire is called from the database and shown by query. so to identify group of radiobuttons for checking which of them choosen in every question I gave different names to every group.(the name is @row.ID: 1 to the inputs of question 1, 2 to question 2.....)

but when I tryed to get the elements by function in javascript, it's not work!!! (I know becouse I tryed to write on screen the length of the "list" by document.write() but sometimes it's zero and sometimes show nothing!!!)

the HTML code is like that:

<form method="post" dir="rtl"> 
        <fieldset class="field"> 
          <legend style="direction: rtl"></legend> 
          <br>
          <div style="direction: rtl" id="questionList"> 
          @foreach(var row in db.Query(displayQuestion))
          { 
              <h3>/question number @counter: </h3>
              <h3>@row.subject: </h3>
              <h3>@row.describe</h3>
              <input type="radio" id="answer1" name="@row.ID" value="@row.ID"
                                                     önchange="chekRadioToAnswer(@row.ID,'1')" >@row.ans1<br>
              <input type="radio" id="answer2" name="@row.ID" value="@row.ID"
                                                     önchange="chekRadioToAnswer(@row.ID,'2')">@row.ans2<br>
              <input type="radio" id="answer3" name="@row.ID" value="@row.ID"
                                                     önchange="chekRadioToAnswer(@row.ID,'3')">@row.ans3<br>
              <input type="radio" id="answer4" name="@row.ID" value="@row.ID"
                                                     önchange="chekRadioToAnswer(@row.ID,'4')">@row.ans4<br>
              if(row.ans5 != null)
              {
                 <input type="radio" id="answer5" name="@row.ID" value="@row.ID" 
                                                     önchange="chekRadioToAnswer(@row.ID,'5')">@row.ans5<br>
              }
              <br>
              counter+=1;

          }
           <input type="hidden" id="hiddenAnswers" name="hiddenAnswers" value="0">

           <input type="hidden" id="hiddenAns1" name="hiddenAns1"  value="0">
           <input type="hidden" id="hiddenAns2" name="hiddenAns2" value="0">
           <input type="hidden" id="hiddenAns3" name="hiddenAns3" value="0">
           <input type="hidden" id="hiddenAns4" name="hiddenAns4" value="0">
           <input type="hidden" id="hiddenAns5" name="hiddenAns5" value="0">
           <input type="hidden" id="hiddenAns6" name="hiddenAns6" value="0">

           <br></br> 
            <input type="submit" value="submit questionnaire" class="submit" />
            <input type="button" style=" float: left" value="skip questionnaire"  önclick="ReDirect()" > 
           <br></br>  

         </div>
       </fieldset> 
</form> 

<script type="text/javascript">
var signAnswers = new Array(0, 0, 0, 0);
    var grades = [[0, 5, 10, 15], [15, 12, 10, 5, 0], [0, 5, 10, 15, 20], [0, 0, 20, 30]];
    var answers = new Array(0, 0, 0, 0, 0, 0);


    function chekRadioToAnswer(numQuestion, numAnswer) {
     if (numQuestion != 1 && numQuestion != 6) {
                var list = document.getElementByName(numQuestion); 
                for (i = 0; i < list.length; i++) {
                    if (list[i].value == numQuestion) {
                        if (list[i].checked) {
                            if (signAnswers[numQuestion - 2] == 0) {
                                var a = document.getElementById("hiddenAnswers").setAttribute("value", value + grades[numQuestion - 2][i]);
                                signAnswers[numQuestion - 2] = grades[numQuestion - 2][i];
                            }
                            else {
                                document.getElementById("hiddenAnswers").setAttribute("value", value - signAnswers[numQuestion - 2]);
                                document.getElementById("hiddenAnswers").setAttribute("value", value + grades[numQuestion - 2][i]);
                                signAnswers[numQuestion - 2] = grades[numQuestion - 2][i];
                            }
                            break;
                        }
                    }

                }
            }

        }
</script>