"add module" Greyed Out

HI, I have 1769-L30REM CompactLogix 5370 with FULLL lisence
and when I when I try to add Module the option is Greyed Out ( only when I online, I can do it when I Offline)
but this is Critical PLC and I must to do it online
I know that its possiable to do it with other PLC like 1756-L72
maybe there is somthing else that block this option and there is a way to fix it?

This isn't a license issue or anything like that, this is fundamental features of the platforms. I don't think you have an option, you add it offline.

Configuration of 1769 series I/O modules is only possible offline. 1756 and 5069 CompactLogix do allow addition of modules online.

use the discover feature, if the module is in the rack, it should discover it. If it's not physically there, then maybe its balking at that feature. I know the compacts don't have hot swap due to how there made, and how the bus is attached, then that attachment at the end of rack for termination of rack. So there is a lot of install features that need you to jump thru before you can add it by discover.