What happend with this???? Britney forgot???

On March 16th the rumor start and was confirmed the next day, and on March 23rd Ellen tweet Britney will be at the show on March 29th but on March 28th the appearance of Britney on 2 skets of the show was POSTPONED and the show was postponed till... when??? what happend betweet Ellen Show and Britney & Crew???? What do u guys think???