Johnny Cash's stepdaughter Carlene Carter is in trouble again. She was jailed yesterday in Gallatin, Tenn., but officials would not say why the 48-year-old country singer was in custody. Nashville TV station WTVF reported her bond had been revoked because she failed a drug test. A court hearing in the case is set for April 12. If convicted, she faces up to 12 years in prison. In December 2002, Carlene was charged with identity theft to obtain prescription drugs. She was also arrested in New Mexico in June 2001 on heroin possession charges. She pleaded no contest in September 2003 and was sentenced to 18 months probation.