Why aren't my DITA <title> elements nesting?

FrameMaker 10 and patched || Windows 7 64-bit

Our company is migrating from unstructured to structured DITA XML.  We had not encountered any "showstoppers" that would keep us from proceeding...until we tried producing FM Book files for our print offerings.  It's my understanding that to take advantage of FrameMaker's numbering and pagination features using DITA source content, one must create a DITA map and save it out as a FM Book file, first.  However, when we do this—and subsequently try to print it like a "normal" book—all of our DITA <title> elements remain at the highest heading level.  In other words, each topic, which lives in a hierarchical structure inside any one of the DITA sub-maps, will always take on the paragraph style of .  My topic titles don't nest; everything is at a "flat" level!   Interestingly enough, they nest correctly if I print directly from a DITA map and not from a hybrid DITA+FM book file.  But if I take that route, I forfeit FrameMaker's ability to create a table of contents, index, etc.—features I can't live without.

I've tried fixing this behavior over the course of an entire week, but I have not had any success.  I cannot find any resources that address this issue, nor can I find anyone with the same issue.  Left to my own devices, I've experimented with re-building the maps numerous times; I've built the maps as plain maps and as bookmaps; I've even tried strange things like conref-ing everything.

What am I missing?  Does anyone know what is going on here?  How can I get my <title> elements to nest?

Some background information:

We place chapters in submaps (one per).

We place those submaps in one, big map.

Any help would be greatly appreciated,

Sean