Radio button list on click function not working in mozilla and chrome

I have a radiobuttonlist in my web application I have an event onclick for this it works fine in IE but not in some other browsers. The sample code is as follows

<asp:RadioButtonList ID="rbgThreadStatus" runat="server" RepeatDirection="Horizontal"
                                                OnSelectedIndexChanged="rbgThreadStatus_SelectedIndexChanged" onclick="return rdblst_onClick();" AutoPostBack="True">
  <asp:ListItem Selected="True" Value="0">Alpha</asp:ListItem>
  <asp:ListItem Value="1">Bravo</asp:ListItem>
  <asp:ListItem Value="2">Charlie</asp:ListItem>
  <asp:ListItem Value="3">Delta Tickets</asp:ListItem>
  <asp:ListItem Value="4">Echo</asp:ListItem>
  </asp:RadioButtonList> <input type="hidden" value="0" id="hdnValue" runat="server" />

Following is the Javascript

function rdblst_onClick()
{
    var hdnValue = document.getElementById('ctl00_ctl00_MainMaster_ContentPlaceHolder2_hdnValue');
    var length = document.getElementById('ctl00_ctl00_MainMaster_ContentPlaceHolder2_rbgThreadStatus').cells.length;
    for (var i = 0; i < length; i++)
    {
        if (document.getElementById('ctl00_ctl00_MainMaster_ContentPlaceHolder2_rbgThreadStatus_' + i.toString()).checked)
        {
            if (hdnValue.value != document.getElementById('ctl00_ctl00_MainMaster_ContentPlaceHolder2_rbgThreadStatus_' + i.toString()).value)
            {
                hdnValue.value = document.getElementById('ctl00_ctl00_MainMaster_ContentPlaceHolder2_rbgThreadStatus_' + i.toString()).value;
                //Some code here
            }
        }
    }
}

Tags: C#, Javascript, HTML, Chrome, ASP.NET