My iphone 4s does not appear in find my iphone

I can run the find my iphone app on both the subject phone and on computers, and it can see my other devices. The time is correct and it's the right icloud account. Still running IOS 5.1.1, which should be sufficient.

I've tried everything in this article: http://support.apple.com/kb/TS4006

I discovered it was broken when my phone was lost for a day (yesterday) and I found it could not be tracked. I got it back, and need to fix the problem.

HELP!

Thanks...