Some child chms don't display topic in topic pane when TOC item is clicked

Okay. I'm not sure what's going on.

We have a master project and various sub-chms that get merged into the TOC of that master project. We have a fairly new sub RH project named "Toolkit Modules" that generates three additional sub chms that are also merged into the master help. They appear at the very end of the master project's TOC:

<master help's toc>

<10 other merged chms>

toolkitmodules.chm

toolkitmodules_blade.chm

toolkitmodules_vwmp.chm

All the topics for the three toolkit modules chms exist in the Toolkit Modules project and are conditionally marked with topic-level build tags so that the right topics appear in their respective chm.

I compiled the three toolkit chms and then put them in the master root directory so that when the master help is generated, they get included properly.

At first glance, all three of these chms appear to be working fine in the master TOC. I can expand and view the master help's TOC for the sub projects just fine, but clicking on a TOC entry does not display

the topics for these two chms in the topic pane:

toolkitmodules_blade.chm

toolkitmodules_vwmp.chm

I'm not sure why.

If I double-click and open up the individual chms from within Windows and view their contents, the topics appear as expected in those chms. It's just when merged, these latter two chms don't do anything from the TOC side. However, I have verified that the topics are indeed getting merged in, because I can use the Search tab to see the topics. In fact, the Locate button on the toolbar even expands the correct TOC and highlights the entry that matches. So something's just not working from the TOC side.

Any ideas?

I'm using RH 9.02.271

Windows 7 64-bit

HtmlHelp output (chm)

Thanks!