That keeps production high, says Mr. Swank.

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"In a more developed market we probably would've sold 5, 000 tickets, " says Sobern from his offices in the swank Mexico City neighborhood of Lomas de Chapultepec.

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Add to the list another requirement: They need to be multi-talented, says Bonnie Liedtke, a William Morris agent long specializing in kid actors from Leonardo DiCaprio and Hilary Swank to High School Musical's Zac Efron and Corbin Bleu.

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