JSON callback works in IE but not FireFox

[jeff00seattle]

I am working on service that is using a JSON endpoint and I am providing it with a JavaScript callback function. The callback function is called in IE (8) but not in FireFox (3.5.3).

The source point to receive the callback is as follows in the body of the page:

<script id="SearchCallback" type="text/javascript" src="">
</script>

The JSON URL with callback doStuff

document.getElementById("SearchCallback").src = json_url_w_callback;

And using online HTTP viewer: http://www.httpviewer.net/, the JSON URL with callback doStuff returns the following JavaScript code:

if(typeof doStuff == 'function') doStuff( /* JSON Results */ );

Ideas why the callback doStuff is not getting called in FireFox?

Thanks

Jeff in Seattle

[jeff00seattle]

{clarifying incomplete sentence} The JSON URL with callback doStuff() is assigned to this source point as follows:

document.getElementById("SearchCallback").src = json_url_w_callback;