''Move Ya Body,'' the breakthrough single by angel-faced duo Nina Sky, is a brilliant gambit from coproducer Cipha Sounds, the New York DJ who helped discover the girls. The twins -- not Jamaicans but Puerto Rican hotties from Queens -- sing harmless party provocations over the conga-matic rhythm track known as ''coolie dance.'' In NYC, where mingling with calypso in sweaty night-clubs has made dancehall a second language among Latinos, a prettily packaged crossover act like Nina Sky is a no-brainer.
But the spare, deliberately tribal ''Move Ya Body'' is just the girls' introductory salvo. Nicole (Ni) and Natalie (Na) Albino are admirably too ambitious to ride the reggae train for their entire self-titled debut. In fact, the uninspired ''coolie'' knockoff ''Turnin' Me On'' is the only other dance-hall ditty. Likewise, Nina Sky is thankfully short on contemporary schlock like ''Holla Back'' and the cookie-cutter crunk of ''In a Dream.'' Nicole and Natalie focus on, and fare better with, stripped-down, throwback R&B. Wistful ''Your Time'' and ''Surely Missed'' recall the gritty melancholy of early Mary J. Blige. (What did you think we meant by ''throwback''? They're only 18.)
Though youth is the twins' liability -- their Dear Diary-ish delivery on ''Runaway'' is as rigid as the drum programming – they overcome thin voices and occasional stiffness frequently enough. And hearing them hold their own alongside old-school diva Betty Wright on ''You Deserve'' kind of makes you glad it's more than just a dancehall ting.