Custom header on posts/pages

I have made a custom Theme based off of twenty ten and for the life of me I can’t seem to get the custom header image to work/change on pages/posts. I want the client to be able to change the header on the individual pages if needed.
What Am I doing wrong?
I go to the admin panel for the page and alter the featured image and choose a header sized image. Isn’t this supposed to change the header image too not just add a thumbnail?
Do I have something wrong? I have kept this part of the header in tact from the ordinal.
I tried switching from my theme back to twenty ten and it still wasn’t working.