Resolving XSD schemaLocation

I was working on an XSD file based off of the XHTML 1.1.

<?xml version="1.0" encoding="utf-8"?>
<!-- Created with Liquid XML Studio 0.9.8.0 (http://www.liquid-technologies.com) -->
<xs:schema     targetNamespace="http://NamespaceTest.com/OrderTypes"
               xmlns:xs="http://www.w3.org/2001/XMLSchema"
               elementFormDefault="qualified">

    <xs:import
        namespace="http://www.w3.org/199/xhtml"
        schemaLocation="http://www.w3.org/MarkUp/SCHEMA/xhtml11.xsd"/>
....

When I try to use Alt+Enter to resolve the schemaLocation it starts well, but eventually I get:

Error while fetching http://www.w3.org/1999/xhtml/datatypes/xhtml-datatypes-1.xsd

I could not figure out where this file came from, and would like a way around this. What am I doing wrong?

Thomas