Super Why! (found stop-motion Nick Jr. pilot of PBS Kids CGI animated series; 1999)
From The Lost Media Wiki
Screenshots from the pliot.
Status: Lost
Super Why! is an animated television show about a kid who jumps into books. The show was created by Blue's Clues creator Angela Santomero in 1999, and a pilot was also made for Nick Jr. by Cuppa Coffee Animation in Toronto, Canada.
The most notable difference between the pilot and the 2007 show is that the pilot was animated in stop-motion animation instead of CGI animation. The designs for the characters also seem to be quite different. No footage of the pilot has surfaced anywhere, however.