Ok, I have these input boxes.

```
<input 
   type="text" 
   name="amount" 
   class="validate[required] text-input" 
   id="amount">

<input type="text" 
       name="incfee" 
       id="incfee" 
       readonly>

```

And this is the javascript I have :-

```
  <script type="text/javascript">
     window.onload = function() {
        var amount = document.getElementById('amount');
        var incfee = document.getElementById('incfee');

        var fee = 0.01;

        amount.onkeyup = function() {
           var result = parseFloat(amount.value) * fee;
           // var result1 = result + amount;
           incfee.value = !isNaN(result) ? result : '';
        };
     }
  </script>

```

Now, the **problem** is, that if I **comment** the line `"var result1 = result + amount;"` and rename result1 to result in **incfee.value** , the value of the textbox (amount including fee) changes with the value in amount and everything works fine.
BUT, If I **uncomment** the line `var result1 = result + amount;` and change result to result 1 in **incfee.value**, the javascript doesn't works and no value is populated in the incfee textbox.
What mistake am I doing?
Thanks.