Pohatu Nuva: People cheating himself with wrong log types
https://www.geocaching.com/help/index.php?pg=kb.chapter&id=107&pgid=534
Found It
You can log caches online as "Found" after you visited the coordinates and signed the logbook. You can also add a photo or a Favorite point to your online log.
Please take time to write at least a few sentences when you log your find — this is how you say “thank you” to the cache owner for creating and placing the geocache.
EarthCaches and Virtual Caches have different logging requirements.
Didn't Find It
Use a “Didn’t Find It” (DNF) log when you look for a cache but do not find it. DNF logs are an important log type — they inform cache owners and other finders that a cache may be extra difficult to find or possibly missing. DNF stands for “Did not find”.