If an install mode is locked, a password box will pop up.  You must ask your administrator to unlock the install mode to do an installation. 

You can tell if an install mode is locked.  Look next to the install mode button for an icon that looks like a lock.  If you see a lock icon, you will be locked out of that install mode. 

In a corporate environment, it is common to lock down the “Off Mode” with a dynamic password.  This offers the greatest protection without allowing the end user to work around it.  In this case, the end user calls the helpdesk; the helpdesk validates the application being installed, generates the password and allows the user to unlock the install mode for one time use.