RICHIE DITCH There’s nothing like a superstar duet to provide good advance press for an album, but sometimes the vaunted guests mysteriously evaporate by the time a project sees the light of day. Last April, EW reported that Lionel Richie and then Backstreet Boys had recorded a Richie tune called ”Cinderella,” but when fans hear the version on Richie’s Renaissance (due out March 20), they’ll find that the Boys, like Cinderella herself, have disappeared from the ball. Jive Records nixed the idea of loaning the boy band out for a project being released so close to their own. Richie’s manager, Skip Miller, notes that not only would the collaboration have been an attention-grabbing single for his client, but ”it wouldn’t have been a bad first single for the Backstreet Boys, either.” (Their ”Shape of My Heart,” off last year’s Black & Blue, was a surprising dud.) … Way back in 1999, meanwhile, we also reported on a reunion between Aerosmith and Run-DMC for a remake of the rappers’ ”It’s Tricky,” set for their Crown Royal album. Now that said album is finally due to hit stores Feb. 27, this collaboration is nowhere to be found, but the circumstances are different: A ”Tricky” backing track was recorded with the Beastie Boys‘ Ad-Rock assisting, but Aerosmith never made it to the studio to record their part. Also dropped from the Run-DMC album were completed hookups with Slick Rick, ODB, and Ja Rule. ”They didn’t fit with the rest of the record,” says Arista’s Pete Ganbarg. Pairings with Sugar Ray, Stephan Jenkins, and others did make the finished product, but only after negotiations with the duet partners’ respective labels delayed Crown Royal‘s release by a year and a half. Going it solo never sounded so good, huh?