The adjustments for v1.3.7 apply to the built-in PayPal support, which can interface with Payflow services only for handling the UK Express Checkout support.
If you're using Payflow as a non-UK merchant and don't have Payflow connected directly to your PayPal account, then simply editing the URL will not suffice ... you'll need to upgrade to v1.3.8a (minimum) and add the free addon for Payflow discussed at the link below:
Payflow Pro module for merchants signed up to use Payflow Pro as their main merchant account/gateway:
http://www.zen-cart.com/forum/showth...988#post481988
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