imap dont show all folders

Question

I work on a webmail with imap, I connet to imap with :

   $IMAPHostname = "localhost";
    $IMAPPort = "143";
    $IMAPFlags = "/novalidate-cert";

I connet with

$Folder="INBOX.Drafts";

$Mailbox ='{'.$IMAPHostname.":".$IMAPPort.$IMAPFlags.'}'.$Folder;
$imap = imap_open ($Mailbox, $session->username."@mydomain.com", $session->password);

I get list folder by :

$list = imap_list($mailbox, "{imap.mydomain.com}", "*");

Output :

"pass","INBOX.Drafts","INBOX.Trash","INBOX.spam","INBOX.Sent","errors reports","Spam","INBOX"

when I try :

imap_append($imap, "INBOX.Drafts", $mail->getSentMIMEMessage(), "\\Seen");

show this error :

"Can't append to mailbox INBOX.Drafts: no such mailbox"

when I get count message in draft return 2 mails. what's wrong?