IE Doesnt Like .innerHTML?

ive got a problem with some of my code. mozilla likes it, but IE gives an error and doesnt do anything with the code what im trying to do is show two fields only if a checkbox is checked. the javascript function is as follows:

function change_permission(){
if(document.category.permission.checked){
document.getElementById('login').innerHTML='<td colspan="2"></td>'
document.getElementById('password').innerHTML='<td colspan="2"></td>'
}else{
document.getElementById('login').innerHTML='<td><div align="right"><font size="2" face="Verdana, Arial, Helvetica, sans-serif">Login: </font></div></td><td><input type="text" name="login" value="{$login}"></td>'
document.getElementById('password').innerHTML='<td><div align="right"><font size="2" face="Verdana, Arial, Helvetica, sans-serif">Password: </font></div></td><td><input type="password" name="password" value=""></td>'
}}

the fields in the form, with default value:

<tr id="login"><td colspan="2"></td></tr>
<tr id="password"><td colspan="2"></td></tr>