Question about PDO stored procedure

Hi, I hope this is the right list to post this too. I am trying to use PDO w/PHP 5.0.5 on Windows. I am calling a stored procedure that has one input parameter and one output parameter. The problem is that if I don't set the value of the return_value to some string before binding the parameter, I get: [Mon Nov 14 11:46:17 2005] [notice] Parent: child process exited with status 3221225477 -- Restarting. So what I end up having to do is: $stmt = $dbh->prepare("CALL TESTPHP.PROCTEST(?,?)"); $cust_key = 'A000000001'; $stmt->bindParam(1, $cust_key, PDO::PARAM_STR); $return_value = 'none'; $stmt->bindParam(2, $return_value, PDO::PARAM_STR, 256); $stmt->execute(); And this works. But why do I need to do this? Thanks, Nell