Can't say that I know the module but it looks as if it's just taking the number without applying the formatting. You could try sprintf - something like:

$wb->write($i, $j, sprintf("%08d", $item), $format);
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UPDATE: I was going to say try a format of "00000000", but rdfield beat me to it

Hey, if there's code up ^^ there ^^, don't blame me if it doesn't work.

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