Google Checkout failure -Oops!

Hi I'm new

I've installed The Google Checkout extension. The actual installation was smooth and all looks well on the site until I press the button to send the info to GC. I get an Oops!. The error message is as follows:

Error: Error parsing XML; message from parser is: Invalid value for attribute name in checkout-shopping-cart/checkout-flow-support/merchant-checkout-flow-support/shipping-methods/flat-rate-shipping: Required field must not be blank
More documentation for this error.
Warnings: XML failed to validate against the schema at line: 1, column 1, with error: cvc-minLength-valid: Value '' with length = '0' is not facet-valid with respect to minLength '1' for type '#AnonType_nameFlatRateShipping'.
XML failed to validate against the schema at line: 1, column 1, with error: cvc-attribute.3: The value '' of attribute 'name' on element 'flat-rate-shipping' is not valid with respect to its type, 'null'.

It's complaining about Flat Rate Shipping being Null, but I'm not using any shipping option at all, I'm determining P&P rates with Country Handler.

I'm running OC v 1.4.9.1 and opencart-1-4-9-11-gcheckout.zip

The only thing I haven't done yet is to set the callback API, as I'm using my GC account successfully with another site that doesn't use it and I don't want to screw that one up whilst testing this one.

I'd really appreciate some help because I'm also new to opencart, php, sql and everything else round here!

Many, many thanks,
Steve
EDIT- OpenCart gives me some info at the top of the page:
Notice: Undefined variable: shipping_title in /home/steve/public_html/shop/catalog/controller/payment/google.php on line 95

I hope it is of help!

Locate the following php page
Catalog>Controller>payment>google.php

Shipping is handled by following lines
$gXML .= '<shipping-methods>';
$gXML .= '<flat-rate-shipping name="' . $shipping_title . '">';
$gXML .= '<price currency="' . $currency . '">' . $shipping_total . '</price>';
$gXML .= '</flat-rate-shipping>';
$gXML .= '</shipping-methods>';

you may try commenting those out lile
// $gXML .= '<shipping-methods>';
// $gXML .= '<flat-rate-shipping name="' . $shipping_title . '">';
// $gXML .= '<price currency="' . $currency . '">' . $shipping_total . '</price>';
// $gXML .= '</flat-rate-shipping>';
// $gXML .= '</shipping-methods>';

Try again all code is in this page regarding shipping
Thanks
Mahesh

First of all, very many thanks for the swift and helpful response. It's solve that particular problem.

However, now that I have go through to the GC routine, I find that the amount to be debited is different from the amount in the Cart.

My cart has goods value and a handling fee (so that I can charge one flat rate for postage in the UK and a different flat rate for international orders). This rate is generated by the Country Handling extension, and this fee is ignored by the GC extension. The GC module appears to send just the goods amount to GC rather than the total Cart value. The reason I bought the module was because the free GC extension did exactly that.....

I'm sure there must be an easy fix, I just wish this was my field of expertise (however, I have invented the best tenon jig in the world - just not much use here though, eh?).

Cheers
Steve

I'd just like to say a public Thank You for the excellent support from Mahesh on this issue. I know have just what I wanted and I've learned a lot along the way too.
Thank you very much indeed.