By Nancy Dillon, New York Daily News (TNS) Bill Cosby was denied parole in his sex assault case this month in part because of his failure to complete a prison program for sex offenders, the Pennsylvania Parole Board said. The comedian isn’t eligible for release until Sept. 25 at the earliest, but the board starts interviewing candidates three to five months in advance and spoke to Cosby by video conference on May 7, board spokeswoman Laura Treaster told the Daily News on Thursday. Based on the interview, the board denied his parole, Treaster said. In a letter detailing its decision, the board …