Why is there no U.S. ambassador to Ethiopia?

I am quoted in Henok Semaegzer Fente's VOA article "Embassies without Ambassadors." Here are my quotes:

Five months after Yamamoto left Addis to become principal deputy assistant secretary in the State Department Bureau of African Affairs, there is no new ambassador in Addis. "It is a mistake," says former U.S. ambassador to Ethiopia David Shinn, "that Washington has not assigned a full-time ambassador to Ethiopia. "The administration should have named someone several months ago. "They are behind the curve already and the longer this drags out, the more difficult it is going to be for the United States to play the role it should be playing in Addis Ababa in the run-up to the election," said Shinn. The embassy is currently headed by Ambassador Roger Meece, who is retired from a lengthy career as a foreign service officer in embassies in central and western Africa. He is on temporary assignment to Addis as charge' d'affaires. ...Shinn said unless the White House names a candidate in the coming two weeks, the process of Senate confirmation will not come in time to place a new ambassador in Addis before the May 2010 elections.