jonas la had been cancelled

i know this is hard for the jo bros fans but disney had cut off jonas la season 3.. the show seems like they have no ending yet.. nobody's know why disney made that decision.. it is because of the jonas brothers do not so popular anymore? or the show do not had the best rating?? all of the disney show had been cut off like hannah montana, wizards of waverly place and now jonas la.. i heard news that sonny with a chance will has no demi lovato because she is sick.. without sonny, how sonny with a chance have?? maybe disney star do not have their power anymore.