isVirtualPayPalBasket not accessible

English forums
1

want to install the PayPal Portlet Module 2.0.0 for PHP5.3 in our OXID CE4.6.0 that is running on PHP5.3.
When I press on the Express-Button or if I select PayPal as payment method I get following error message:

Function ‘isVirtualPayPalBasket’ does not exist or is not accessible! (oxBasket)

The class oxbasket seems to get extended:

2

what about the things described here:
http://forum.oxid-esales.com/showthread.php?t=14494
?