paypal error

Hello,

I had marketpress working with paypal ok, then yesterday I updated to new version of wordpress and latest version of marketpress 2.4.1

During order process, after selecting paypal from payment options this error comes up –

There was a problem connecting to PayPal to setup your purchase. Please try again.

10400 – Transaction refused because of an invalid argument. See additional error messages for details. – Order total is missing.

Each item has a price total, and the cart shows a total. Any ideas?