What’s going on? First, Dane Cook’s Broadway debut was postponed and now his sitcom has been canceled — before it has even aired. The Hollywood Reporter says NBC, which had ordered six episodes of “Next Caller,” has pulled the plug on the show starring Cook as a foul-mouthed radio host. The reason: It wasn’t “heading in the creative direction” the network had in mind. While it’s possible someone else will pick up the show, it’s not clear anyone’s interested. Cook, who hails from Arlington, was supposed to make his stage debut last year in a production of Neil LaBute’s “Fat Pig,” but the show was pushed back because an investor dropped out.