For all those That's So Raven fans out there, the disappearance of Raven's mum, Tanya Baxter, in the Disney Channel show's final season has always been a bit of a mystery. But T’Keyah Crystal Keymáh is now setting the record straight as to why she really left the show nearly a decade ago.In an interview with Madame Noire , the In Living Colour star said she didn't leave because of money, bad blood, or being tired of the character, she left because of her grandmother who had Alzheimer's.Keymáh says in the first season of That's So Raven, her grandmother was diagnosed, but as the season's continued her grandmother's condition got worse. The actress said she had "wonderful caregivers," but her grandmother needed more help on a daily basis.This was hard with Keymáh's shooting schedule, but she said everyone at the show was very supportive."The cast and the crew were just phenomenal and I will always be grateful to them because by that point my grandmother was so combative that I couldn’t keep a caregiver for her," she said. "So I was bringing her to work with me. And Kyle [Massey] and Orlando’s [Brown] mum would watch her in my dressing room while I was on stage. And that just couldn’t go on."That's why when Keymáh's contract was up after three seasons, she decided to put her grandmother first. The show then wrote Tanya off the show in its fourth season by saying she had moved to England to attend law school."It was the hardest thing I hope to ever do in this life," Keymáh said. " I’m really, really glad I was able to do it. And I would do it again in a heartbeat — I wish I could — but it took everything out of me."After leaving the show in 2007 to care of her grandmother, which she did until her passing, Keymáh said she considered herself "retired," but in the last few years has started working again. She has a supporting role in the college, comedy, What Happened Last Night, produced a film called Revival, and has a cameo in the next Sharknado film.While it's been awhile since she played Raven-Symoné's mum on TV, Keymáh still has love for her fictional telepathic daughter. When asked about some of Symoné's more controversial comments on The View, Keymáh made it clear she wasn't having it."I love my baby. Don’t mess with my baby. Don’t say anything," she said laughing. "You know how some people are, if you look like you’re saying something against Barack Obama…don’t you mess with my baby."That's so Raven's mum.