I have a sony xplod 400 watt amp and two 12' kickers but my kickers dont have sound at all. Help Please!?

I connected the ground to a good and secure spot and Replace the wires inside the kickers box and replace the wires outside the box. The amp has power and everything looks like its connected good. i have no clue what it can be. Can anyone please help me figure out or give me a clue as to what it can be please. Thank you.