Discussions about Quests

[Deluxxe]

I often see where someone is asking to harvest a give crop so they might complete their quest. I guess I don't understand just how the quests work. When I have certain crops that are needed to fill a spot on my quest and I work someones farm I do not get credit for that harvest in my quest. So, either I'm doing something wrong or is it that all quest have to be worked just off my own farms.