i wrote to dave palmer a little while ago and here is what he said
Thanks so much for watching the show! I was also upset when I heard we weren't going to be do another season--I really love the show, and loved directing it. Honestly though, I can tell you that the odds of doing another season are not good.
I'll let the rest of the Backyardigans team know how much you like the show, and hope you keep watching. Thanks again, and all the best,