That Magic Moment is the first part of episode 8 in season 3 of Dexter's Laboratory that aired on June 14, 2002. In this episode, Dexter's uncle Fergle O'Reilly comes to visit and makes Dee Dee disappear. Dexter then tries to get his sister back.
Although this episode aired in 2002, it was produced in 2001 according to the credits.
This episode completed production in July 2001.[1]
According to the end credits, the variation of Cartoon Network Studios with Dexter and Dee Dee with black background has been replaced by the white background.