It won't be a family affair for the Jacksons at this week's World Music Awards in London. While Michael Jackson will be there on Wednesday to pick up the Diamond Award, which is given to artists who sell more than 100 million albums, his little sister, Janet Jackson, isn't exactly welcome—unless she picks up her own tab, that is.

I hear Ms. Nasty would have been one expensive guest. Cost of bringing her to the show is said to have been estimated at a whopping $400,000. Why so high? Private jet, hotel stay, hair and makeup and, of course, expenses for her gazillion-member entourage.

Unfortunately, Janet just doesn't pull the power she once did. For those of you who don't remember, it was a big coup in 1993 when Michael and Janet appeared on stage together at that year's Grammy Awards. Upon receiving the Grammy Legend Award from Janet, Michael joked from the stage, "I hope this finally puts to rest another rumor that has been in the press for too many years—me and Janet really are two different people."

"If her new album was a hit, then maybe they would have paid for her to come to London," an insider says. "But she's just not worth it right now."