[tbworld]

This should work:

PHP Code:

    global $vbulletin;

    // error processing for the datamanager if needed.
    require_once "d:/servers/z421/web/bbs/includes/adminfunctions.php";  
 
    // Existing User
    $userid  = 6;             // Existing User ID
    $newusername = 'david1';  // New user name string (cleaned)

    $userdata =& datamanager_init('User', $vbulletin, ERRTYPE_CP);
    $userinfo = fetch_userinfo($userid);
    $userdata->set_existing($userinfo);
    $userdata->set('username', $newusername);
    $userdata->save();
    unset($userdata); 


I ran a quick test.

Looking at what you were doing, I am guessing you can take it from here.