Google Checkout - order notification failing

I am getting errors from Google saying that it can’t notify my cart of the checkout process.

What API version should I be using inside my Google Checkout Account? Currently I am using 2.5, should this be one of the lower ones?

My company will only post digitally signed carts is Checked

I am using [url][/url]

Notification is set to XML

And the Notification Filtering is UNchecked.

Inside of CS-Cart my settings are

The I Accept is Checked

My Merchant ID and Key are set and verified against Google and correct.

US Dollar

Live Mode

And no default values for shipping.

The error I am getting from Google says

[QUOTE]We encountered an error processing your notification acknowledgment. The error we got is: Expected serial number was not contained in notification acknowledgment. [/QUOTE]

The XML they received

[HTML]<?xml version="1.0" encoding="UTF-8"?>[/HTML]

And the XML they sent is a huge long thing with lots of information inside of it.

If I can provide you more information, just let me know. I think I have version 2.1 of CS-Cart, let me know where I can check on this and I can verify, but I downloaded it from here just a couple of weeks ago as a trial thing.


Can anyone help me with this issue?