I got a note that:
if u want to set a mail to "//Unseen", which not exists,
do it like this:
imap_clearflag_full($your_imap_connection,
$number_of_message,"//Seen");
but, remember to do
imap_close($imap, CL_EXPUNGE);
@ the END! so that it will be confirmed!
Cheers,
Nohado