By XML schema rules, it is specifically stated that the schema file does not have to be present on the Web. (However, I think this is highly desirable, to guarantee uniqueness of schema and hence the document format.) So, don't worry about it. The schema is known by the WiX code; this is all that matters.
As to the problem with the
RegistrySearch
element, please see the schema documentation:
http://wixtoolset.org/documentation/manual/v3/xsd/util/[
^],
http://wixtoolset.org/documentation/manual/v3/xsd/util/registrysearch.html[
^].
See also:
http://wixtoolset.org/documentation/manual/v3/xsd/wix/registrysearch.html[
^].
I did not try this element; and you did not show the relevant piece of code, so I cannot check up if it is correct.
—SA