If at first you don’t succeed, try, try again. After years unsuccessfully trying to sell his 4,000-square-foot co-op unit in 1045 Park Avenue, developer Joseph Moinian has finally found a buyer. The real estate mogul sold the five-bedroom penthouse on the 15th floor to Robin Rankin, head of mergers and acquisitions at Credit Suisse. She paid $8.8 million for the pad, according to Department of Finance records.