function disableTextBox(popUp, textBox) {
  var myindex  = popUp.selectedIndex;
  var SelValue = popUp.options[myindex].value;
  
  if ( SelValue != "No Symbol" ) {
    var activeTextBox = document.getElementById(textBox);
    activeTextBox.value = "";
    activeTextBox.disabled = true;
  
    var tempName = activeTextBox.name;
    activeTextBox.name = "disabled" + textBox;
    //alert(activeTextBox.name);    
  } else {
    var activeTextBox = document.getElementById(textBox);
    activeTextBox.disabled = false;
    activeTextBox.name = textBox;
    //alert(activeTextBox.name);    
  }
}