I have a similar issue.
on Linux 2.6.18-408.el5.lve0.8.61.1 x86_64
Our online store is based in Australia. We would like to use Paypal Payflow Link as our only payment method. We have to select “United States” as the Merchant Country in the Payment Method Configuration page.
The issue is within the “Paypal Payflow Link (Includes Express Checkout)” payment method. In the configuration for this payment method, there are no fields to input the Vendor Id, Username or Password.
This results in the following error when trying to checkout
“Some required information is missing or incorrect. Please correct the fields below and try again.
? Error: Merchant Design Identification Error.”
The above error is known to be caused by incorrect credentials.
The following was tracked in the http headers when trying to checkout (using Google Chrome version 24.0.1312.57 m)
<form id="token_form" method="POST" action="https://payflowlink.paypal.com/">
<input type="hidden" name="SECURETOKEN" value="7Mg1G9iAKBkK9P3lg2nMMMQhx" />
<input type="hidden" name="SECURETOKENID" value="4cdfa96836d32b29d7bcde89ed4a7420" />
<input type="hidden" name="MODE" value="TEST" />
Paypal and Magento Config screenshots can be downloaded here: