Sometimes the simplest things cause the biggest problems. In this case it's the Subform/Subreport linking feature of Access. My application uses a two-field primary key that links two tables together and this works perfectly with Access forms. However when I try to use the same technique in the report module, it just does not work. Period.
A Google search returned no pertinent posts about this problem. However testing has shown that a single field key works in both contexts. The solutions seems to be to add a extra key (Autonumber field) to the tables just for reporting purposes. I hope this post somehow gets indexed and saves someone else from the frustration of finding a work-around for this issue.