NEW YORK: A fifth season of “Mad Men,” the US series retro-set in the 1960s New York advertising world, has been confirmed but will not be broadcast before March 2012, the AMC network said Tuesday.

The news from AMC, which has broadcast the series every summer for four years, drew some disappointed reactions from fans looking forward to seeing Don Draper – the hero played by Jon Hamm – in new shows a few months from now.

AMC confirmed Tuesday it has ordered the fifth season from Lionsgate, the company that produces the series.

But it said filming would be delayed “due to ongoing, key non-cast negotiations,” according to an AMC statement.

The network has had problems with Matt Weiner, 45, who writes and produces the series, industry media say. He reportedly has not been warm to AMC's demand for each episode to be cut back in order for more advertising to be fit in, and for some of the cast to be trimmed to cut costs.

In an interview with The New York Times, Weiner confirmed as much saying “the cuts would make Mad Men 'a different show.” “I don't understand why, with all of the success of the show, they suddenly need to change it,” he added.

“All I want to do is continue to make my show, and make it in the way I want to, with the people I want to make it with.” The Times cited an unnamed source close to the negotiations as saying Weiner had been offered a three-season deal worth a record 30 million dollars, which he has not accepted.

The series, a hit in the United States and abroad, has won three Emmy Awards for best series in 2008, 2009 and 2010.