Other mistake: I was so bugged by protocol errors in early episodes that I stopped watching. For example, there were at least 2 episodes where Navy or Marine officers in utility uniforms were wearing Army brass on their collars. In one episode, "Harm" is walking with his female partner through a garage. He returns the salute of an enlisted man who walks by, but she doesn't. In any event, the garage was indoors, where Naval Service protocol says you don't salute.
Other mistake: After the first meeting with the JAG team and Secretary Blair to negotiate The Return of the F-14, Captain Fuente refers to Meg as "lieutenant commander". Harm is the LCDR; Meg is a lieutenant, junior grade. It's not just a character mistake: Meg's shoulder insignias indicate her rank. (00:24:30)
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.