apple id format for using find my iphone

You need to change your old Apple ID to one with an email address. Here is some info from a FaceTime document ( http://support.apple.com/kb/HT4319):

Ensure that the Apple ID you are using to register FaceTime on iPod touch (4th generation) is an email address. If your Apple ID is not an email address, you can change it on appleid.apple.com. This article provides instructions on how to change the Apple ID.

"appleid.apple.com is":
https://appleid.apple.com/cgi-bin/WebObjects/MyAppleId.woa/
"This article" is:
http://support.apple.com/kb/HE40

I am having a similar problem. I enter my Apple id with password (which I use to log into iTunes store etc etc all the time without a problem) but when I try to add it in the Add Account, Mobile Me part it comes back and says unsupported Apple ID and that it requires an Apple ID which is an email address. So I put in my apple id with the email part (my Apple id is in fact the first part of my email) and my password but when it tries to verify it says username or password is incorrect?? What is going wrong. I have 4.2.1

Do I have to go into Add Account, Mobile me, then Create Free Apple ID to use this function??? Will this affect my original Apple ID or is it only used for the Mobile me app??

Thanks I changed my Apple ID to an email address and now it works fine. Thanks very much