Implementing Google checkout : Adding tax to shipping

[ultim]

Hi,
I am having problems adding tax to my shipping.
I have tried the following code

<input type="hidden"
	name="checkout-flow-support.merchant-checkout-flow-support.shipping-methods.flat-rate-shipping-1.name"
	value="UK Delivery"/>
	<input type="hidden"
	name="checkout-flow-support.merchant-checkout-flow-support.shipping-methods.flat-rate-shipping-1.price"
	value="20.00"/>
	<input type="hidden"
	name="checkout-flow-support.merchant-checkout-flow-support.shipping-methods.flat-rate-shipping-1.price.currency"
	value="GBP"/>
	<input type="hidden" name="checkout-flow-support.merchant-checkout-flow-support.tax-tables.default-tax-table.default-tax-rule-1.shipping-taxed" value="true"/> 
	<input type="hidden"
	name="checkout-flow-support.merchant-checkout-flow-support.tax-tables.default-tax-table.tax-rules.default-tax-rule-1.rate"
	value="0.175"/>

The shipping cost shows up but tax is not getting added. Anyone know what I am doing wrong?