execQuery: No query engine found

Hi all.

I'm aware this is a recurrent problem but I haven't, for the best of my
abilities, been able to understand what's going on.

I'm running XMLBeans 2.4.0, from the Maven repo and when I'm trying to make
a selectQuery on a XmlObject I get the "No query engine found".

Now I've tried with Saxon 9.3.0.4j and 8.8.0.7j and both fail. I'm certain
that the saxon*.jar is in the classpath. What else can I do?
I've thought about downgrading XMLBeans to 2.2 or something... would this be
worth it? If so, what version of the xmlbeans-maven-plugin should I use
(currently 2.3.3)?

Thanks,
Henrique Nunes