Why not continue the story where the original left off?

The filmmakers of Return of the Living Dead II made the same mistake as the Italians did with Demons 2. Instead of proceeding immediately where the original ended, they changed course and attempted to rehash the original. Demons 2 was not bad. It at least had better characters, but ROTLD II was hard to watch (my main beef was the writing, annoying characters - mainly Lucy, Brenda, and Ed, and choosing a kid as the main character). This film could have been better if they set the story in multiple locations (the clouds carrying acid rain could travel to neighboring states setting the stage for an epidemic), created better characters, hired more talented actors, and if they had directed this film for adults instead of teens.