changed logic board now no service

Ive recently change the logic board on an iphone 4 from a previous phone that i had smashed...the one i had took out was water damaged...so after changing thr mothrr board it finally booted it up i restored it but once it was at the point to follow steps to setup phone it doesnt wanna go any further then the wifi part it just just no sims card found...why is his...i really need help