paypal error


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?