Not able to use Facetime on Ipad3 using Wireless

Hi there! I am having a hard time using Facetime on my Ipad3. I have also tried to Facetime my husband and son while I was away using my Iphone, while they were home on the Ipad. But they would not connect. Is there some kind of complication if the apple ID and email account is the same on both devices? Should one device have the apple ID and the other have an email address in to connect to? Any suggestions would help! Thanks!