Dear all,
according this blogpost
http://www.shoptimax.de/blog/technisches/prufung-umsatzsteuer-identnummer/
the European Union changed the URL for it’s webservice to check the VAT ID again. Our developers could second that and will deliver version 4.5.0 with the new URL
http://ec.europa.eu/taxation_customs/vies/checkVatService.wsdl
Please make the necessary changes manually in your admin panel of your OXID eShop Enterprise Edition < 4.5.0.
Regards