[URGENT] cant turn On in admincp

[geevest.com]

im upgrade my vbulletin version.... before im using vbulletin 3.67 and now im using vbul 3.68.
but i have some problem in 3.68... i can login admin in my admincp.but if i want to turn On my Vbulletin again,always ask me to login.
....why?

----------------------------------------------------------------------------------------------------
vBulletin 3.6.8 Admin Control Panel

To continue this action, login using the admin account that intiated the action

username :
Password :
----------------------------------------------------------------------------------------------------

[Paul M]

Try logging out of VB completely and then login again.

[geevest.com]

i have been try but there is no way out to solve my problem...

[Marco van Herwaarden]

Please upload tools.php from the 'do_not_upload' folder of your vBulletin distribution to your admincp directory. Now point your browser to tools.php.

Reset the cookie Domain and Path to the default values.

Once your problem is fixed please remove tools.php again from the server.

If this does not solve your problems, please clear your browser cookies and cache, restart your browser and try again.