tkda said:

Somehow, during my play, 

I was able to build "Trading Center" without researching Nuclear thing...

and Now, it is not letting me to research nuclear thing, nor efficiency.

I am basically do anything from there.

even after I payed extra to get crystal and stuffs, 

I cannot upgrade to use my novice shield effientlly 

Sounds like a bug, you should submit a ticket to support so they can fix it for you.  https://support.plarium.com/entd/Tickets/Submit/Category/20