>I found the problem. If the project name has a period in the middle of the filename, Code References generates the "_ref" file without the ".dbf" extension. Therefore, when time comes to display the search result, it can not find the file with the ".dbf", and therefore assumes there were no result from the search.
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>Either I need to change my naming convension for filename in my most recent application, or not to expect the Code references to work as expected.

There's third choice. You can submit bug to MS and try to fix the Code References and rebuild the application. Fixing could be as easy as adding '.' to the following list in the foxref.h

* The following are invalid in an alias name so we replace with '_'
#define INVALID_ALIAS_CHARS	" -@#$%^&*()+={}[]:;?/<>,\|~`'" + ["]