Working with FrameMaker, when you use the menu (DITA > New DITA File) and choose a topic type (topic, task, concept, reference), FrameMaker creates a new file that starts with the "dita" element.

 If you plan to create small FrameMaker files that will be components of longer files (such as several topics that will later be combined into a chapter file), note that you will need to ensure your component files do not start with the "dita" element. 

When you combine your files in a map and have FrameMaker produce the combined file (DITA > Build FM Document From DITA Map), FrameMaker brings the component files in, and if they start with "dita" you can end up with an invalid structure in your combined file ("dita" elements where they aren't supposed to be).

To get rid of the "dita" element, each time that you create a new file in Frame (DITA > New DITA File as mentioned before), take a moment to select the "dita" element and from the menu choose Element > Unwrap.  This let's you get rid of the unneeded "dita" element.  Your file will now start with the appropriate "topic", "task", "concept", or "reference" element.  It can be saved, used in map files, etc.

Good luck!