[javascript] document.getElementById().value and document.getElementById().checked not working for IE

I tried to assign a new value into the hidden input and checkbox of an input form. It's working fine in Firefox but not in IE (I'm using IE 7). Does anyone know what is wrong with my code?

HTML:

<input type="hidden" id="msg" name="msg" value="" style="display:none"/>
<input type="checkbox" name="sp" value="100" id="sp_100">

Javascript:

var Msg="abc";
document.getElementById('msg').value = Msg;
document.getElementById('sp_100').checked = true;

For non-grouped elements, name and id should be same. In this case you gave name as 'sp' and id as 'sp_100'. Don't do that, do it like this:

HTML:

<input type="hidden" id="msg" name="msg" value="" style="display:none"/>
<input type="checkbox" name="sp" value="100" id="sp">

Javascript:

var Msg="abc";
document.getElementById('msg').value = Msg;
document.getElementById('sp').checked = true;

For more details

please visit : http://www.impressivewebs.com/avoiding-problems-with-javascript-getelementbyid-method-in-internet-explorer-7/