SELECT records less than 15 minutes old

[sono-io]

Hi,

	I'm trying to write a statement that will return all records that match a particular
order_id and that have a timestamp within the last 15 minutes.  I thought that this
should work:

SELECT * FROM `records` WHERE `order_id` = $order_id AND (`time_stamp` >=
DATE_SUB(NOW(), INTERVAL 15 MINUTE))

but it returns zero rows, no matter what.  If I up the interval to something huge, like
15000, it will then return records.  Very strange.  It's almost like it's using seconds,
not minutes.

	Is my syntax wrong?

Thanks,
Marc