I can't download iOS 6 or later?

I have an iPad 2 and to update it says in setting general software update to update to it… It worked on my iPhone but not on my iPad 2… Why? Please help!

Added (1). Like it doesn't say it on iPad 2 to update to it.

IPad 2, that iOS 4? Or is it iOS 5, can't remember, see if this article will help: http://support.apple.com/.../kb/HT4972