Twitter's advertising revenue will reach US$150 million in 2011 and $250 million next year, according to digital marketing research company eMarketer.Twitter Bible: Everything You Need To Know About TwitterHowever, in order to have long-term business success, the microblogging and social networking company will have to work extra hard to ensure that this first wave of marketers gets the expected results from their ad spending, eMarketer said Monday."If Twitter can grow its user base and convince marketers of its value as a go-to secondary player to Facebook, it will succeed in gaining revenue," said Debra Aho Williamson, an eMarketer principal analyst, in a statement. "In 2011 it must work overtime to give its early advertisers a positive experience."Most of Twitter's ad sales this year and in 2012 will come from the U.S., just as they did in 2010, when the company generated $45 million in revenue, according to eMarketer estimates.By comparison, Facebook closed 2010 with US$1.86 billion in revenue, according to eMarketer, which forecasts that the social networking leader will generate $4 billion this year and $5.7 billion in 2012.Meanwhile, eMarketer sees MySpace's revenue on a downward slide from $288 million in 2010 to $184 million this year and $156 million in 2012. MySpace laid off 500 employees, or about 47 percent of its global staff, earlier this month.