Getting the nested gridview values when it is inside the content placeholder in javascript

function  Rdbtn(index)
{
   var gridView1 = document.getElementById('ctl00_ContentPlaceHolder1_GVBenefit');
 
   var billamt=0;
   var billamt_tot=0; 
   var input4 =  gridView1.rows[index - 1].getElementsByTagName('input')[6]; 
   var idExt=index;  
    for (var i = 1; i < gridView1.rows.length; i++)
    {
          if(parseInt(idExt,10) <= 9)
          {
           idExt = "0" + idExt;                     
          }  

            var VExtGrid = "ctl00_ContentPlaceHolder1_GVBenefit_ctl"+idExt;              
            var gridView = document.getElementById(VExtGrid+"_GvSubBenfits");       
             for (var j = 1; j < gridView.rows.length; j++)
             {  
                   var inputs1 = gridView.rows[j].getElementsByTagName('input')[0];
                   var inputs2 = gridView.rows[j].getElementsByTagName('input')[1];
                   var txtAdm = gridView.rows[j].getElementsByTagName('input')[2];

                   if( inputs1.checked==true )
                   {
                    txtAdm.setAttribute("disabled", false);       
                   }
                    if( inputs2.checked==true )
                   {
                    txtAdm.setAttribute("disabled", true);       
                   }
                 
                   if (txtAdm.value.length<1)
                   {
                     billamt=0;
                   }
                   else
                   {
                     billamt =parseFloat(txtAdm.value);
                   }
             
                billamt_tot = billamt_tot + billamt;
              
                input4.value = billamt_tot;
             }
             GetAppAmt();
      }   
  
}