No password passed from php "auto"login form

[FabZ]

Hi all,
I installed RC 0.42 and it works fine.
Then I created several RC autologin forms on my site (for testing porpose), I used any modified autologon.php and autologin.php listen on forum and elsewhere but I have always the same problem: NO password field filled, only the username one...
I have no related errors logged on server.
Any hint?
Thanks