Jimmy Carter's sister, Gloria Spann died in 1990, why did Carter not give a statement to the press?

Spann died at only 64 in 1990 of pancreatic cancer. Carter was asked by the press for a statement, which he declined. Was there some sort of unresolved conflict between Carter and his sister? He gave a statement for his brother, Billy in 1988 who seemed far more controversial during the Carter administration than Spann ever was. Does anyone know the reason behind this?