Head to Toe - S7-E15
Factual error: Lt.Col. Sarah Coffey wears the USAF uniform, but an Army insignia on her left collar (the MI "splatted bug"). An Air Force officer wears identical insignia on right and left collars (a dark oak leaf, in this case).
Factual error: Lt. Singer is wearing the wrong epaulets (shoulder boards). She is wearing the epaulets with a star on it instead of the legal emblem.
Answer: Officially, the individual has been ordered to attend, failing to could be interpreted as either, Failure to follow orders, dereliction of duty, going AWOL, or even desertion. It would depend on the underlying reason as to why the person doesn't appear.