Mysql_num_rows() Error in Activation Script

[shatteredroses]

Hello again.
I've been recoding a section of script that's refusing to run for no apparent reason and have encountered a whole new set of issues.
The script I'm running basically retrieves a username and password from the link a user clicks on in their activation email, and updates their account to activated.
It then double checks that the account is activated, and lets them know of any problems.
The error I'm getting is:

Warning: mysql_numrows(): supplied argument is not a valid MySQL result resource in /home/hollowd/public_html/login/activate.php on line 15

And the script I'm running looks like this:

<?

//Establish the database connection
$conn = mysql_connect("localhost", "hollowd_php", "******");
$select = mysql_select_db("profiles", $conn);

//Request the info from the URL
$userid = $_REQUEST['id'];
$code = $_REQUEST['code'];

//Activate the users account
$update = mysql_query("UPDATE profiles SET activated='1' WHERE userid='$userid' AND password='$code'");

//Check account is activated
$sql_check = "SELECT * FROM profiles WHERE userid='$userid' AND password='$code' AND activated='1'";
$check = mysql_query($sql_check, $conn);
$result = mysql_num_rows($check);

//Let the user know the result
if ($result == 0){
PRINT "Your account could not be activated, please contact [email][e-mail][/email]";
} elseif ($check > 0) {
PRINT "Your account has been activated. You may now log in";
} else {
PRINT "Something happened, I don't know what but it just ain't right";
}

?>

I seem to be returning this "supplied argument is not a valid MySQL result resource" error a lot . . . Am I reading it right in assuming it occurs when the data fed to mysql_num_rows is wrong in some way?
If so, how can I fix it in this script?
Thanks in advance,
Roses

[lilleman]

Hi,

An error-message like that often indicates that the SQL-query failed. Try changing your code to
this and see if you get an error-message from MySQL.

$check = mysql_query($sql_check, $conn) or die(mysql_error());

Yours, Erik.

[yelvington]

You should check the returned value of a query before proceeding. If the returned value is FALSE, that means the query could not be executed. Don't pass a FALSE value on to any other function. Instead, call mysql_error() with no arguments and echo the results. It should explain something about what you did wrong.

I suspect your problem may have to do with quoting a non-string value in your SQL.

[shatteredroses]

Thanks for your help.
Now when I run the script, I keep getting 'Your account could not be activated' and the following error in my error log:

PHP Warning: Unknown(): Unable to load dynamic library './ixed.lin.4.3.9.pxp' - ./ixed.lin.4.3.9.pxp: cannot open shared object file: No such file or directory in Unknown on line 0

I had this problem with the code before I rewrote it, and got on to my hosters who said they had no idea what the problem was after reinstalling PHP, editing the php.ini file and restarting Apache and still not fixing the problem.

Do you have any idea what I can do, or what I can get them to do to fix this error?
What causes it?
Thanks again