Cannot Access the MODx Manager Control Panel

When I try to access the manager (http://thedomain.com/manager), I am redirected to main home page of the website (http://thedomain.com). Please help.

Is this a new install? What version of modx, php, etc?

---------------------------------------------------------------------------------------------------------------
PLEASE, PLEASE specify the version of MODX you are using . . . PLEASE!
MODx info for everyone: http://bobsguides.com/MODx.html