SOPERA Validation error - importing schemas? [solved]

[SidKennedy]

Today I got the following error in the problems view when I create a new Sopera Project:

SOPERA Validation: XSD Validation: ['org.xml.sax.SAXParseException: cvc-elt.1: Cannot find the declaration of element 'definitions'.']
for any sdx-file
and

SOPERA Validation: XSD Validation: ['org.xml.sax.SAXParseException: cvc-elt.1: Cannot find the declaration of element 'wsdl:definitions'.']
for any spdx-file

I'm kind of helpless how to resolve this issue. Can anybody help me?