By any chance if you haven't been able to lock your options within the stipulated time frame, the system will lock the options for you. The server will lock the options for automatically after the last day. So that is when it shows that the options have been locked by the system. You cannot lock it on your own because the system has locked them for you. But there is nothing to be worried. The pop up shows the way it is because your options have been automatically locked and not manually locked. Read this for more information: https://mcc.nic.in/UGCounselling/Documents/UGSchemeFinal.pdf