<input onclick=validate not working?

it is not validating the amt1 input box?
Any idea why?


<script language="JavaScript" type="text/javascript">
            <!--
            function validate()
            {
                    if(document.test4.Amt1.value == '0')
                        {
                          alert('Please enter donation amount greater than $0');
                         document.test.Amt1.focus();
                        return false;
                        }
                  document.test4.submit();
            }
            //-->
            </script>

<form name="test4" style="color: #000080;" action="submit.asp" method="get">
<table style="width: 400px; height: 150px">
<tr><td colspan="2"></td></tr>
<tr><td>Program</td><td>
<select name="programURL">
<option value="">Select Program </option>
</select>
</td></tr>
<tr><td>Amount</td><td><input name="Amt1" size="8" maxlength="8" style="width: 70px; height: 20px;" class="style9" value="0"/></td></td></tr>
<tr><td colspan="2">
<input type="image" src="Donate.gif" border="0" name="submit" width="92" height="26" class="style5" onclick="javascript:validate();">

            
</td></tr></table>

</form>