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I'm getting a 400 error with this xml conent
 <?xml version="1.0" encoding="utf-16"?>
<entry xmlns="http://www.w3.org/2005/Atom">
<title> </title>
<updated>2008-07-23T14:21:06.407Z</updated>
<author />
<id>http://constantcontact.com</id>
<summary type="text">Contact</summary>
<content type="application/atom+xml">
<Contact xmlns="http://ws.constantcontact.com/ns/1.0/">
<EmailAddress>martineztek@gmail.com</EmailAddress>
<OptInSource>ACTION_BY_CONTACT</OptInSource>
<ContactLists>
<ContactList id="http://api.constantcontact.com/ws/customers/martineztek/lists/1" />
</ContactLists>
</Contact>
</content>
</entry>
Any thoughts as to why I'm getting this?  Thanks!