Hi Im doing the dkp by hand, filling people's dkp manually person by person, and every so often every raid I get about 2 or three people per raid where their dkp goes from 200 to zero, i dont understand it.

That might be the creepiest avatar ever.

What you'll want to check out is head to Admin > DKP > Quick Edit Destinations. It sounds like one of your ranks is giving 0% to members for the selected destination.

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It's all in the reflexes.