What was “Milkshake,” anyway? R&B? And now that you think about it, isn’t it kind of weird to categorize what Kelis did in “Caught Out There” as singing, or what was going on in “Bossy” as rapping? Kelis has been a risky oddball from the get-go. On her fifth album, she sounds like she’s finally found her calling in Eurodance. There’s “Acapella”’s spare, forthright throb and the eerie roller-disco synths that propel “Home.” But Fleshtone takes too long to get to the good stuff. “22nd Century” and “4th of July (Fireworks)” grow more generic with each listen. Many of the best moments happen between the tracks, with loopy, cutup endings and odd experimental twists. If only Kelis were as confident in her songwriting as she is in her ambition to skitter up a record. As it stands, she’s a failed innovator and an undervalued singles artist.