Healing during FATEs = no credit?

[Risky]

To add, unlike other actions performed during a FATE, healing/shielding/buffing doesn't require you be synced to the FATE.
In order to participate in a FATE, you must sync to it. If the FATE level is close to your level, you automatically sync.
If the FATE level is not close, you must manually sync.

The FATE is a level 39 FATE, as a L54 healer it is easy to start concentrating on healing and forget to sync, as you can still heal the group or others outside the group while not-synced.
As others above said, you need to do at least one point of damage in order to be added to the enmity table of the FATE and you can only do damage while synced.
I have flubbed this a few times, forgetting to sync and try to participate ...oops.
So, always double check you are synced before attempting a FATE, in party or not.

Something to also consider when doing FATEs is that you have chance to get full credit if you engage with them when they are nearing completion. And this rule would be per player arriving. If you were one of the last ones to the area, saw that people needed healing or raising, focused on healing first, and did not get the needed damage hits in then you may not have had enough time to get participation credit. (I am not saying this happened though in this case.)

Someone syncing with a fate near completion, joining a party that dealt the majority of damage, and getting in 1 damage would receive full gold credit, correct?
I have done run-by heals towards strangers as they engaged with a fate while I was passing through but I would sync if I were staying to engage. I recognize that this is exploitable in a more deliberate way which would create an imbalance with fairness. This makes a lot more sense on a technical aspect as to why the devs chose to require damage as part of receiving credit but exploiters will exploit. I wonder if the devs can reduce the effectiveness of heals from unsync'd PCs to sync'd PCs during a fate... This would increase the spirit of fairness with fates throughout the community. If you are participating with the fate, you should have skin in the game.

After the initial surprise and disappointment of not receiving credit, I realized that I did not do any damage and that was the reason (see my initial post). This thread was more for awareness to others and I'm enjoying the clarification. Thanks all.