AO won't display anymore

I googled this and came up with nothing. I had AO working in my scene just fine. After awhile it stopped working and I can't get it working. I made a new post chain and plugged in a new AO node and hooked it up to world post process chain and it will not work no matter what I try. I don't get why it was working fine before and not anymore.

I am not at home so I can't get pictures until later.
Thanks.