Maybe it's the wrong password.
The best thing to try: change the password in the router and see if the new password works. Start with a simple one.
Kees
I just got lg smart TV lg47620t and got the dongle it picks up my WiFi great signal but when I put in my password it says no network connection what's wrong.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic