This show started out with great mystery episodes. I think everyone is in the first 15 or 16 episodes. After that, the show started playing short episodes with Shaggy, Scooby doo, and Scrappy doo.<br /><br />I think Hanna Barbera Productions had to change 20 minutes episodes into short episodes. Some of the voice actors became unavailable. After 15 or 16 episodes, Frank Welker (who played Fred) became unavailable. I think the voice of Velma changes after first 12 episodes, because the first voice actress who played Velma was unavailable.<br /><br />And the network ordered the Hanna Barbera studio to make more shorts with Shaggy, Scooby doo, and Scrappy doo, because the ratings were high. So they had to make more shorts. I wish they were mysteries like 15 episodes. Still it is a good show.