I'd change the default `catalog/product/price.phtml`

I've tried already:
    
    <reference name="catalog_product_price_template">
         <action method="addPriceBlockType"><type>simple</type><block>catalog/product_price</block><template>catalog/product/custom-price.phtml</template></action>
    </reference>

but using `xdebug` I've seen that the `addPriceBlockType` method is not used for the `simple` product, so it returns the default template.

where I'm wrong?
thank you