Cannot apply master page!

[Nancy Allison]

Hi, all. I have a new problem. When I generate an index, as usual the 
result is unformatted; however, it doesn't look like a regular 
freshly-generated index. It looks as if it's using a master page from my 
TOC file.

But I've checked; only the correct IOM master pages are in the IOM file.

When I use Format/page layout/master page usage and apply the master 
pages as I have done a million times before, nothing changes on the body 
pages. (It's easy to tell, because all my IOM master pages have two 
columns. The weird generated page has only one.)

I've tried everything, including creating a new book file from scratch. 
Every generated file I add (TOC, LOF, LOT) is perfectly formatted EXCEPT 
the IOM, which continues the same weirdness as before.

I've tried importing formats from my clean template IOM, which works 
fine in *its* book file.

No dice.

Helllllp!