Is this the line you put in your /etc/pam.d/common-auth?
instead of havingCode:auth sufficient pam_krb5.so
Of cource after installing libpam-krb5.Code:auth sufficient pam_winbind.so
I wasn't getting a ticket at logon either, and making the above changes took care of it for me. I now get one at each logon. BTW, I didn't touch my common-account for this.