DITA XML output format missing one topic when exporting. How can I diagnose the problem?

We are using Knowledge Center. The DITA XML output format that I think comes from SDL, uses MSXML 4.0 as the style processor. In the log file it fails to a copy one of the topics in the baseline, because it wasn't exported. Do you know  how I can diagnose the problem? Other output formats export the topic.

Regards,

Kendall