semantic mediawiki template query issue

Question

I have inherited a template and I am trying to extend it. The template has a query like this:

[[IsSubjectOf::<q>[[-IsTargetOf::<q>[[HasReferenceDataset::SomeReferenceDataSet]]</q>]]</q>]]

This returns the subjects in the targets that are in the specified ReferenceDataset.

Now we have a new type, ResultSet. A result set contains 1 or more ReferenceDatasets. I want to add one more level of subquery to get the subjects in the targets that are in ReferenceDatasets in the specified ResultSet. I tried this (along with 100 other things):

[[IsSubjectOf::<q>[[-IsTargetOf::<q>[[IsReferenceDatasetOf::<q>[[HasResponseSet::SomeResponseSet]]</q>]]</q>]]</q>]]

But I get nothing back.

[[HasResponseSet::SomeResponseSet]]

Does return the ReferenceDatasets in the ResponseSet, but

[[IsReferenceDatasetOf::<q>[[HasResponseSet::SomeResponseSet]]</q>]]

returns nothing. Anyone see what I am doing wrong here?

Also what is the meaning of the leading - in front of IsTargetOf?