Cannot join Active Directory, no manual helps. Any ideas?

Hi all,

I have been trying for hours to integrate my VMware vCenter with Active Directory ;-( Unfortunatelly, Web Client and vSphere Client grant only my root account (root@localos). I have no idea what the master password or admin password could be. Also, when I log in to Web Client there is no Configuration item in Sign-On and Discovery area and SSO Users and Groups are missing too. I have a version 5.1.0 of VMware.

Any help?