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Big Day Out organisers are warning concert-goers to check their ticket numbers after 21 disappeared from Sounds music stores throughout the country over about four weeks.
"We gave them to Sounds to sell but they claim they don't have them so we're not really sure if they were stolen from the store or by staff or what," promoter Campbell Smith said.
He had been trying to find out what had happened since the stores went into voluntary administration last month but was not being given clear answers.
As part of the Big Day Out's anti-scalping initiative for 2008, barcode scanners will be in operation at all Mt Smart Stadium gates.
