Does the Request Log state no relevant changes for that DC?
The log will contain a message like "Activation contains no relevant changes for this component" for the DC in question.
The CBS skips the build of the DC in this case. Therefore no build log is created. That means that the DC actually contains no relevant sources or defines no source/package folders.
You should check the DC's source and package folders and ensures that the declared folders actually contain the sources of that DC.