Sorry I didn't get back to you sooner I don't have Internet at the new apartment yet. If I could offer some things to look at related to your question, why was Jesus preaching in hell?
1 Peter gives us a few verses that talk about this specifically
3:19 - "By which also he went and preached unto the spirits in prison;"+
4:6 - "For for this cause was the gospel preached also to them that are dead, that they might be judged according to men in the flesh, but live according to God in the spirit."
This happened to fulfill a prophecy given back in Isaiah 61:1 -
"The Spirit of the Lord GOD [is] upon me; because the LORD hath anointed me to preach good tidings unto the meek; he hath sent me to bind up the brokenhearted, to proclaim liberty to the captives, and the opening of the prison to [them that are] bound;"
I wish I had more time to expound on these, but I can say that text does show that Jesus did preach to the dead in hell, or prison. The purpose may include to simply show them there fault, show them that they had an opportunity to have eternal life but they rejected it. Also, it should be noted that Jesus did take those in Paradise into Heaven upon His ascension .
Open to comments...