Children's Fiction Books Bestseller List for April 4, 2002 from sales the week ending March 31 For the Book Sense store nearest you, call 1-888-BOOKSENSE or visit www.booksense.com   CHILDREN'S FICTION BOOKS   1. Stage Fright on a Summer Night - Debut Mary Pope Osborne, 0375806113, Random House, $3.99.   2. The Adventures of Super Diaper Baby Dav Pilkey, 0439376068, Blue Sky, $4.99.   3. The Bad Beginning Lemony Snicket, 0064407667, HarperTrophy, $9.95.   4. Harry Potter & the Prisoner of Azkaban J.K. Rowling, 0439136369, Scholastic, $7.99.   5. Princess in Love - Debut Meg Cabot, 0060294671, HarperCollins, $15.99.   6. Harry Potter & the Chamber of Secrets J.K. Rowling, 0439064872, Scholastic, $6.99.   7. Princess in the Spotlight - Debut Meg Cabot, 0064472795, HarperCollins, $5.95.   8. Harry Potter & the Sorcerer's Stone J.K. Rowling, 059035342X, Scholastic, $6.99.   9. Harry Potter & the Goblet of Fire J.K. Rowling, 0439139597, Scholastic, $25.95.   10. A Single Shard Linda Sue Park, 0395978270, Clarion Books, $15.   11. The Sisterhood of the Traveling Pants Ann Brashares, 0385729332, Delacorte, $14.95.   12. Bud, Not Buddy Christopher Paul Curtis, 0440413281, Yearling Books, $6.50.   13. Because of Winn-Dixie Kate DiCamillo, 0763616052, Candlewick, $5.99.   14. The Wide Window Lemony Snicket, 0064407683, HarperTrophy, $9.95.   15. The Reptile Room Lemony Snicket, 0064407675, HarperTrophy, $9.95.     ON THE RISE   32. Ruby Holler Sharon Creech, 0060277327, Joanna Cotler Books, $16.95. The story of two orphans who finally find a home by the Newbery Medal-winning author.   The Book Sense Bestseller List is copyrighted and cannot be reprinted without permission from the American Booksellers Association. For information, please contact Sascha Alper, Book Sense Projects Manager, at: (914) 591-2665 ext. 1202, 828 South Broadway, Tarrytown NY. Reprint Guidelines.