Source file doesn't properly rebuild after header change

[Steve Lewis]

I have a project in MS VC 6.0 that was generated through the ATL Com
wizard. There are several .cpp and .h files that have been added to the
project. One .h file includes a #define. This same .h file is included
in three of the .cpp files. When I open the .h file and change the
definition of the #define, then build the project, all of the affected
files are rebuilt except one. One of the .cpps is skipped (no changes
detected), so the preprocessor does not replace the #defined symbol in
that source file with the changed definition.

The compiler output looks like this:

Compiling...
manager.cpp
Generating Code...
Skipping... (no relevant changes detected)
Indexer.cpp
Worker.cpp
Linking...

ndIndexer.exe - 0 error(s), 0 warning(s)

Any ideas? Why do two of the files get properly rebuilt, but not the
third? (indexer.cpp). All 3 .cpp files #include the same header file
with the #define.

Thanks for any help,

Steve Lewis
seden...@yahoo.com