calling stored procedures from php problem...

[Calimlim Michael Angelo]

can any1 help me with my problem with calling stored procedures from php.....
the problem i having is the code sometimes gives an error sometimes it does not.......
can any1 help me find the problem.....
thanx for the help! :D

here is my code in mysql and php.....

mysql

create proceudre sp_test(out p_out char(255), out p_msg char(255), in p_val int)
begin
/*some sql queries here*/

if p_val > 15 then
set p_out = 1;
set p_msg = 'The number is greater than 15';
else
set p_out = 0;
set p_msg = 'The number is lesser than 15 ';
end if;
end

grant execute
on procedure db.sp_test
to usr@'host';

php

$val = 25; //can be any number.....

$db = new mysqli("host", "usr", "pwd", "db");

if (mysqli_connect_errno())
{
echo "Connection error";
exit();
}

$sp = "call sp_test(@out, @msg, ".$val.");";

if ($result = $db->query($sp))
{
if ($result = $db->query("select @out, @msg;"))
{
$row = $result->fetch_array(MYSQLI_BOTH);

echo $row[0]."<br>";
echo $row[1]."<br>"; //sometimes the query succeeds here
}
else
{
echo "Error!"; //sometimes gives an error here :(
}
}
else
{
echo "Error!";
}