Howard hires Potsi to sing at his 25th anniversary party on April 1 in exchange for $500. On March 1, Potsi calls Howard and tells Howard that he cannot sing for Howard on April 1, as he is going on a trip to Hollywood on that day. Howard then calls Ralph on March 2 and asks Ralph to sing instaed of Potsi. Ralph agrees and Howard and Ralph agree to a contract under which Ralph will sing at the party, also for $500. On March 4, Pots calls Howard and states that he can come to the party after all. Howard tells Potsi that he hired Ralph instead. Howard refuses to pay Potsi and Potsi sues Howard for the $500. Will Potsi be successful? Explain.