<tr valign=top>
<td>$notes</td>
<td>$intnotes</td>
- <td><select name=payment_id onChange="set_duedate(['payment_id__' + this.value],['duedate'])">$payment
+ <td><select name=payment_id onChange="if (this.value) set_duedate(['payment_id__' + this.value],['duedate'])">$payment
</select></td>
</tr>
</table>