QTI v2.1 validation

As a newbie, I was trying to validate one of the examples from the QTI v2.1 download in Liquid XML Studio. It failed.
It seems that the cause of failure is the different use of versions of the xml.xsd - in imsqti_v2p1.xsd, it is declared as
<xsd:import namespace="http://www.w3.org/XML/1998/namespace" schemaLocation="http://www.w3.org/2001/xml.xsd"/>

whereas when it imports, the imslip_v1p0.xsd, it is declared there as
<xsd:import namespace="http://www.w3.org/XML/1998/namespace" schemaLocation="http://www.w3.org/2001/03/xml.xsd"/>

Although some reference to validation problems are mentioned in the Validation section of http://www.imsglobal.org/quest...1pd2.html#section10021 , the solution offered did not seem to tally with what is in the document.

Workaround:

I downloaded both locally and altered the line
<xsd:import namespace="http://www.w3.org/XML/1998/namespace" schemaLocation="http://www.w3.org/2001/xml.xsd"/> to be identical in both imsqti_v2p1.xsd and imslip_v1p0.xsd. Then the examples e.g. choice.xml do validate.

There are also issues in the common-attribs.xsd as they use a null
<xsd:import /> which is not liked. Maybe that Liquid is too sensitive or that things are not quite as tight as they might be.