Q: When I connect to iTunes it says my 9.2.1 software is the latest version after I check for updates

Iam tring to update my iPad air from 9.2.1 to 9.3.1 I get the errs message unable to verify because I am not connected to the internet, so I connected to my iMac and opened iTunes and clicked on check to update and it says 9.2.1 is the latest version.