How to use Custom Namespace for a Google Merchant Center Item Feed

Question

I have declared the namespace that i am using:

<?xml version='1.0'?>
<entry xmlns='http://www.w3.org/2005/Atom'
           xmlns:g='http://base.google.com/ns/1.0'
           xmlns:c='http://base.google.com/cns/1.0'&gt;

here is a typical xml node i have:

<c:gold_type type="string">White Gold</c:gold_type>

Yet, when i submit my feed only the Google Namespace xml nodes work.

Any ideas?