I'm in pretty much the samer situation as everyone else.
Please keep the suggestions coming everyone - I have a feeling some people are getting a solution, but because this is a complex issue the explanations need to be clearer.
For those suggesting to simply select the option of 'change your primary email account'...... that doesnt help most of us becasue it either just refershes the page or tells us the email address is already associated with another account.
If you think you have solved the real problem, please post a description that is unambiguous about which changes you make to which account.
ALSO.......IS ANYONE FROM APPLE LISTENING OUT THERE????
Finally a workaround!!
I've had the same problem using the "make primary email my Apple ID" button. Nothing happens. The page just refreshes. So here's what worked for me:
1. Login to your account online (https://appleid.apple.com) and go to Manage Account.
2. Edit your primary email address to another valid email address. Don't worry, you can change it back.
3. Go the new email's inbox and find the email from Apple asking you to verify this new address. Click Verify.
4. Go back to Manage Account and try using the "make primary email my Apple ID" button again. It should work now.
5. Now go back to your iphone and login with your new Apple ID credentials.
6. If you want, go back to Manage Account and change your Apple ID back to your original email address.
You'll find more info at this post:
I think this post can probably help everyone http://www.macstories.net/stories/ios-5-icloud-tips-sharing-an-apple-id-with-you r-family/ . The important thing I realized is that you can have different Apple IDs for different purposes within iOS5. I was previously getting the same error message when trying to add my iTunes ID to the Store section of the Settings. I finally resolved it by signing out of the old ID that I don't want to use under the Store settings. It then asked if I wanted to use the existing ID. I checked yes, entered my iTunes AppleID and everything worked fine.
Hope that helps.