Prime Minister Narendra Modi will not be able to attend AAP chief and Delhi Chief Minister-elect Arvind Kejriwal's oath taking ceremony here Saturday, party leader Manish Sisodia said Thursday.Sisodia told media that owing to the prime minister's schedule, Modi will not be able to attend the swearing-in ceremony."I would have been happy to attend, but I will not be able to," Sisodia quoted Modi as saying.He spoke to reporters after he and Kejriwal met Modi at 7 Race Course Road here.Kejriwal is scheduled to take oath Saturday at the sprawling Ramlila Maidan in the heart of the national capital.