''What's your sign?'' sighs Alison Goldfrapp, as serrated synth lines zigzag across ''Train.'' Her second album is one sultry pickup line after another, set to sidekick Will Gregory's pulsing electro-pop: Slow, breathy singing massages the jagged ''Crystalline Green,'' while ''Tiptoe'' shimmies from bouncy strut to windswept epic. When backbeats disappear, though, boring dirges (''Deep Honey'') and space-age Muzak (''Hairy Trees'') ooze out. Rock the dance floor, Alison, but spare us the elevator music.