This works, it is hard to do,but it really can work.

At the end of each day, even a bad day. I try to tell my daughters thanks for at least one good behavior. For example I will say thank you for putting your dishes in the sink after dinner. They love the additional praise and it usually puts a smile on their faces right before they fall asleep.

Thank you so much for your great advice! I did try this and as hard as it was to ignore the screaming, I did it. When she could see I wasn't going to give in this time, she stopped screaming, she walked over to me (I was sitting on the floor pretending to read) she put her nose to mine, so were eye to eye and nose to nose---I think she was making sure she had my full attention, and I smiled and made a silly face, and then I hugged and tickled her...she laughed so hard and so did I....
Thanks for your help. I'm going to keep on trying this!

Anytime you ignore behavior in order to promote a much better behavior you need to remind yourself that any behavior will get worse before it is extinguished. If it ever worked (the screaming) once, it is hard for her to give it up. Just keep rewarding the possitive behavior and telling yourself that it really does work. Also try to catch her with a reward (praise) before the screaming starts and look for a trigger that might start her screaming (in the afternoon when she's tired, when she wants a drink, after the t.v. is turned off, etc.) and see if you can establish a link that you can contol. Don't forget to look at both before and after the screaming for a link. It takes a while, but it so worthwhile in the end.