Hello guys,

I have a part of html form like this one below...
Code:
<form name="Subscribe" action="https://select.worldpay.com/wcc/purchase" method="post" />
<table width="400" border="0" align="center" cellpadding="0" cellspacing="4">
  <tr>
    <td colspan="3"><img src="../images/common/logo_popwin.gif"></td>
  </tr>
  <tr>
    <td colspan="3">Select Subscription Type</td>
  </tr>
  <tr>
    <td class="BlueSmall">Individual</td>
    <td>
      <input name="amount" type="radio" value="1" />Selection One
    </td>
    <td>
      <input name="amount" type="radio" value="2" />Selection Two
    </td>
  </tr>
  <tr>
    <td>Corporate</td>
    <td>
      <input name="amount" type="radio" value="3" />Selection Three</td>
    <td">
      <input name="amount" type="radio" value="4" />Selection Four
    </td>
  </tr>
  <tr>
    <td>Other Amount</td>
    <td colspan="2">
      <input name="amount" type="text" class="Input190" onFocus="AmountClear(this)"
... which works with this JavaScript to uncheck the radio buttons when a user onFocus on the text field.
Code:
function AmountClear(amountField) {
  if (amountField) {
    for (i=0; i<document.Subscribe.amount.length; i++) {
      if (document.Subscribe.amount[i].value != "") {
        document.Subscribe.amount[i].checked = false
      }
    }
  }
}
Is it possible to write a script to clear the text field when a user checks one of the radio buttons? The trouble here is both radio buttons and text field have a same name "amount". This is because the form is submitted to a third party online payment system which I can't change and I have to use the name "amount" for transaction to happen. Please help.