THEATER : A ‘Peanuts’ Gallery : Child actors impress and delight the 18-year-old director of ‘Snoopy,’ a musical opening at Van Nuys’ West End Playhouse.

After a promising start in commercials and theater, Dahlia Mia was washed up last year at 9.

“I got braces,” said Dahlia, “and nobody likes to hire someone with braces. My agent didn’t send me out on anything.”

This year, however, the braces are off and the career is back on track. Dahlia will play Peppermint Patty in “Snoopy,” a former off-Broadway musical based on the Charles Schultz comic strip “Peanuts,” opening Saturday at West End Playhouse in Van Nuys.

“I’m looking forward to the part,” said the young Bel-Air resident, who played “Annie” at the Showboat Youth Theatre in Encino in 1990. “She’s really insecure and always worried whether people like her. That’s very different from me, so I will have to expand.”

Erica Horne, 12, shares a similar anticipation. She will portray the demanding Lucy, a role she, too, considers a stretch.

“She likes to have her way and, if she doesn’t get it, she cries,” Erica, of North Hollywood, said of her character.

Erica has always been interested in acting, especially for television. But at first she feared that it would take her from her family.

“I was too scared because I thought that you had to live in the TV. One day, when I was about 5, I finally told my parents that I was ready to leave them and live inside the TV. My mom said, ‘OK, Erica,’ and took me to an agent.”

The story amused Lisa Matthews, 18, a Cal State Northridge sophomore who will direct the play. She pitched “Snoopy” to several theaters across the San Fernando Valley and spent $1,000 to $2,000 of her own money to find the play a home at the West End. She auditioned about 70 child actors in two months to find the double cast of 14--two groups of seven who will alternate performances.

“This is the most fun I’ve ever had,” said Matthews, who directed and choreographed “You’re a Good Man, Charlie Brown” at the West End in 1991. “I’d give them a break, and instead of resting, they would go to the piano and practice the hardest song.”

Matthews made her directorial debut at Wilbur School in Tarzana when she was 8. She directed one scene from “Annie” as part of a class activity and never hid her motivation.

“I wanted to be Annie and that was the way to do it,” Matthews said. She directed her second play, “The Red Sneaks,” about a high school girl who becomes addicted to materialism and popularity, last year at thA. Connection Theatre in Sherman Oaks. Unlike the other two plays, this one featured adult actors.

“Snoopy” was originally performed by this cast in January at North Valley Jewish Community Center in Granada Hills. But eight performances were not enough.

“Especially when you rehearse for so long,” Matthews said.

Most of the actors she found have performed in theater or television. Erica played Roseanne Arnold’s youngest daughter on the HBO special that served as the blueprint for Arnold’s hit ABC-TV sitcom.

“She was a lot of fun,” Erica said, although she added that she never was called to audition for the show.

Danielle Marcus-Janssen, 14, of Camarillo, who plays Snoopy, has done plenty of television and appreciates the opportunity to try theater. She appears daily on the Disney Channel’s Emmy-winning series, “Kids Incorporated,” in which teen-agers dance to pop hits and participate in story lines dealing with the problems of their peers.

“In television, you have to do what they say,” Danielle said. “In theater, you can use your own ideas.”

Where and When What: “Snoopy.” Location: West End Playhouse, 7446 Van Nuys Blvd., Van Nuys. Hours: 3 p.m. Saturdays through May 9. Price: $7. Call: (818) 904-0444.