Problemi con menù a tendina PHP - MySQL

[Alhazred]

Così che fa?

<select type="text" id="tipo" name="tipo" value="" />
<?php 
    $query = ("SELECT DISTINCT type_doc FROM ".DB_PREFIX."docs");
    $result = mysqli_query($db, $query);
    if ($result == false) 
    {
        mysql_errno();    
        echo "<option value=''></option>";
    }
    else
    {
        while($row = mysqli_fetch_array($result, MYSQLI_ASSOC))
        {
?>
        <option value="<?php echo $row['type_doc'] ?>"><b><?php echo $row["type_doc"] ?></b></option>";
<?php
        }
    }
?>
</select>