It doesn't seem like there is a problem, I can't understand why doesn't return data.
This is my stored procedure:
DELIMITER $$
DROP PROCEDURE IF EXISTS `test`.`get_products`$$
CREATE PROCEDURE `test`.`get_products`
(
OUT out_productName VARCHAR(255)
)
BEGIN
SELECT productName INTO out_productName FROM products;
END $$
DELIMITER ;
and this is how I call it:
$rs = mysql_query( 'CALL get_products(@f)' );
$rs = mysql_query( 'SELECT @f' );
while($row = mysql_fetch_assoc($rs))
{
print_r($row);
}