minecraft.novylen.net

I began a skyblock world recently and I tried to "/challenge complete cobblestonegenerator" after I had made the generator and obtained 64 cobble. Upon entering this command, the console said, "Unknown challenge name (check spelling)!" I checked my spelling, entered, and received the same result. I am wondering if this is an error on my part or an error or the system's part.

Thank you,
MikeTheEpic