[Greasemonkey] document.createElement returns null

[Fabien Bergeret]

I've already posted few days ago (was "inserting a script on a HTML page") : it didn't work 'coz the object I was setting the innerHTML attribute was null.
But why was it null ? 
Here is a code sample : 

function addDiv() {
	var div = document.createElement("div");
	GM_log("Div created "+div);
	div.setAttribute('id','converter');
	div.setAttribute('style','position: absolute; background-color: #FFFF00; visibility: hidden; padding:5px; border: 1px solid #000; color: #000; text-align: center;');
	log("Div attribute set");
	document.body.insertBefore(div, document.body.lastChild);
	log("Div inserted");
}

The first line of the function creates a correct div on amazon.com for intance, but return a null value on ebay.com. Any idea why ?
Thanks !

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