如何将变量与mysqli_stmt_bind_param（）中的参数进行匹配

Question

对此有些奇怪，将不胜感激。

$rs_contact = mysqli_prepare($conn, "
SELECT CONTACTID, COMPANY, FORENAME, SURNAME, MATCH (FORENAME, SURNAME) AGAINST ('?') AS relevance 
FROM CONTACTS
WHERE MATCH (FORENAME, SURNAME) AGAINST ('?')
ORDER BY relevance DESC
");
mysqli_stmt_bind_param($rs_contact, "ss", $q_string, $q_string);// bind parameters
mysqli_stmt_execute($rs_contact);// execute query
mysqli_stmt_store_result($rs_contact);// store result - needed for longtext fields
mysqli_stmt_bind_result($rs_contact, $CONTACTID, $COMPANY, $FORENAME, $SURNAME, $relevance);// bind result variables
$rowcount_contact = mysqli_stmt_num_rows($rs_contact);

这将返回错误

Warning: mysqli_stmt_bind_param() [function.mysqli-stmt-bind-param]: Number of variables doesn't match number of parameters in prepared statement in /search.php on line XX

这不是我第一次使用多个参数，而是我第一次必须对两个参数槽使用相同的变量。

这可能是一个简单的小学生错误，但我看不到。

谢谢